Source: Explosives Found in Suspicious Packages Packed Powerful Punch

(CNN) -- Two suspicious packages found abroad that were bound for Jewish organizations in the United States contained a massive amount of explosive material that -- had the suspected terror plot not been thwarted -- would have triggered a powerful blast, a source close to the investigation said Friday.

U.S. officials believe that al Qaeda in the Arabian Peninsula, commonly referred to as AQAP, is behind the plot.

President Barack Obama confirmed that the packages -- intercepted in the United Kingdom and the United Arab Emirates -- originated in Yemen, the stronghold of al Qaeda in the Arabian Peninsula.

"We also know that al Qaeda in the Arabian Peninsula ... continues to plan attacks against our homeland, our citizens, and our friends and allies," he said during a press briefing on the incident.

One suspicious package, found at the UK's East Midlands Airport, contained a "manipulated" toner cartridge and had white powder on it as well as wires and a circuit board, a law enforcement source said. A similar package set to be shipped on a FedEx cargo plane was discovered in Dubai, the law enforcement source and Dubai officials said.

"Initial examination of those packages has determined they do apparently contain explosive material," Obama said.

The source close to the investigation said the type of material found in the devices was PETN, a highly explosive organic compound belonging to the same chemical family as nitroglycerin. Just six grams of PETN is enough to blow a hole in the fuselage of an aircraft.

PETN was allegedly one of the components of the bomb concealed by Umar Farouk AbdulMutallab, the Nigerian man accused of trying to set off an explosion aboard Northwest Airlines Flight 253 as it approached Detroit, Michigan, on December 25. AbdulMutallab is alleged to have been carrying 80 grams of PETN in that botched attack -- also believed to be the workings of al Qaeda in the Arabian Peninsula.

By comparison, the source said the two devices found Friday contained multiple times more PETN. The source also said it appears the devices were designed to be detonated by a cell phone with the help of a smaller amount of a second unidentified explosive substance.

The cell-phone theory was seconded by a wireless engineer for a major U.S.-based manufacturer, who analyzed a photo of one of the devices at CNN's request.

"This size and the shape of the PCB (printed circuit board) are typical to a handset cell phone type device," wrote Olivier Clerc, hardware application engineering manager for a cell-phone-parts manufacturer.

Both packages were bound for the United States, "specifically two places of Jewish worship in Chicago," Obama said.

The packages led to increased searches of cargo planes and trucks in several U.S. cities, said law enforcement sources with detailed knowledge of the investigation.

White House counterterrorism chief John Brennan said that "the materials that were found and the device that was discovered were intended to do harm."

Brennan said the discovery of the packages was made with help from Saudi Arabia, and issued a statement thanking the country for its "assistance in developing information that helped underscore the imminence of the threat emanating from Yemen."

A source with firsthand knowledge of the information told CNN that the Saudi Arabian government gave the United States tracking numbers of the two packages, allowing for quick tracing to the United Kingdom and Dubai.

Senate Intelligence Committee Chairwoman Dianne Feinstein, D-California, called the potential plot "a new novel thing -- and that is using FedEx and UPS planes to perhaps bring in something that might be explosive."

The Transportation Security Administration issued Friday afternoon a halt in the United States on all packages originating from Yemen, and shipping companies UPS, FedEx and DHL all said they were complying with the order.

Sen. Susan Collins, the ranking Republican on the Senate Homeland Security Committee, told CNN she is very concerned about holes in the system to screen cargo coming into the United States, said that had a credible intelligence source not warned about the suspicious packages, they may not have been detected with standard security procedures.

Collins, who was briefed by TSA chief John Pistole, said intelligence officials do not know yet if this was part of a larger plot, but she does believe al Qaeda is "continuing to test for vulnerabilities in our security system, and it appears we do have vulnerabilities in our system for transporting cargo."

After the packages were found Thursday night and Friday morning, authorities were tracking other packages shipped from Yemen in the same time frame, a law enforcement source said.

A Yemeni diplomat in Washington said that his government has opened a full-scale investigation into the incident but that it was too early to speculate or reach any conclusions.

Counterterrorism officials are taking the threat "very seriously," Obama said.

The Department of Homeland Security said it "had taken a number of steps to enhance security," including "heightened cargo screening and additional security at airports."

Some Jewish religious leaders in Chicago were alerted to the potential threat Friday, said Linda Haase, spokeswoman for the Jewish Federation of Metropolitan Chicago.

"We were notified about this earlier this morning," she said. "We are taking appropriate precautions, and we are advising local synagogues to do the same."

Rabbi Marvin Hier of the Simon Wiesenthal Center in Los Angeles, California, said that if synagogues were indeed the intended recipients of the packages, "this is just another indication of the dangerous world we live in where Jews are the principle target."

Meanwhile, U.S. authorities seemed most focused on inspecting cargo planes.

Investigators examined two UPS planes that landed at Philadelphia International Airport in Pennsylvania and another at Newark Liberty International Airport in New Jersey, said Mike Mangeot, a UPS spokesman. Authorities later gave the "all-clear" at both airports, the Transportation Security Administration said.

The TSA said authorities acted "out of an abundance of caution."

Connecticut Be Buggin' Today!

BRANFORD, Conn. — Police and FBI agents Friday night said a tractor-trailer stopped in Branford, Conn., and suspected of carrying explosives was empty, NBC station WVIT of Hartford reported.

Branford first selectman Anthony DaRos earlier said police told him authorities were holding the semitrailer at a travel stop on Interstate 95.

The Hartford Courant reported troopers approached the vehicle and took the driver and a passenger into custody at gunpoint, then checked the vehicle for hazards. It also reported that the state police bomb squad was en route.

Police were told to be on the lookout for a brown Peterbilt tractor-trailer that may have a bomb in it that was en route from Rhode Island to New York City, the New Haven Register reported. Officers were told if they encountered it to stop it and create a perimeter and stand by.

Branford is about 80 miles north of New York City.

In another incident, around 6:21 p.m. Friday, a Connecticut state trooper shot and killed a motorist after what police said was a routine traffic stop on I-84 near Danbury, the Courant reported. Danbury is about 45 miles away from Branford.

The driver opened fire on the officer, who returned fire and shot the motorist multiple times. The trooper was uninjured, the Courant said.

The two passengers fled.

The highway was closed in both directions Friday night.

On Wednesday, two men were found in a Mercedes with what appeared to be a pipe bomb, ammunition, gas masks and other materials. Authorities say it's unclear whether they planned to use the explosives because they are not talking to investigators. Both were being held on $500,000 bond.

Passenger: Terror Suspect Seemed 'Stunned'

(CNN) -- Syed Jafry was preparing for his plane to land in Detroit, Michigan, after a long flight from Amsterdam, Netherlands, when he heard a noise that startled him.

"There was a little bit of light, a little bit of -- kind of flamish light and there was fire," Jafry told CNN. "And people began to panic."

For a couple of seconds on Northwest Flight 253, nobody knew what was going on, he said.

That pop, officials say, came from a Nigerian man who ignited a small explosive device as the flight descended into the Detroit, Michigan, area. The White House described the incident as an attempted terrorist attack. The suspect was eventually subdued by passengers and crew.

As the commotion began, passengers didn't know what to think.

Jafry said he thought the man looked to be in his 20s.

Passenger Elias Fawaz told WDIV that the detonation sounded "like a balloon being popped" and said he could smell smoke.

That's when he saw a struggle in the cabin.

"We heard, 'What are you doing?' 'What are you doing?' " Fawaz told WDIV.

Within seconds a young man on the flight took matters into his own hands, according to Jafry and other passengers who spoke to CNN affiliate WXYZ-TV.

A man, sitting three or four rows behind Jafry jumped over a group of seats, tackled the suspect and put him in a headlock.

"He handled him pretty good, I think," Jafry said.

Jafry said other passengers and crew members then helped subdue the man and put out flames after the suspect's pants appeared to catch fire.

People screamed.

"Everybody was rushing towards that area and tried to get water," Jafry said, adding that people rushed the man with blankets and a fire extinguisher.

"They put out the fire, brought him up front where they stripped him down to make sure that he had nothing else," passenger Melinda Dennis told CNN affiliate WDIV.

Other passengers told WXYZ the injured suspect was put in the first row of first class.

"He appeared to be more stunned and surprised with the whole act," Jafry said of the suspect after he was subdued.

Passengers, including Jafry, said they could see the suspect was burned on different parts of his body, but he didn't seem to say much or act as if he were in pain.

Jafry said soon after the suspect was moved to the front of the plane, the crew and pilot told passengers the incident was under control.

"And we were on the ground, I think between 10 to 20 minutes after the incident," Jafry said.

Jafry and other passengers were screened again and questioned for about four to five hours before finally being able to meet their friends and family, or reach connecting flights.