Romulus, Michigan (CNN) -- A Nigerian man is "talking a lot" to the FBI, said a senior U.S. official, after what the United States believes was an attempted terrorist attack on an inbound international flight.
The initial impression is that the suspect was acting alone and did not have any formal connections to organized terrorist groups, said the senior official who is familiar with the investigation.
The suspect, identified by a U.S. government official as 23-year-old Umar Farouk Abdulmutallab, ignited a small explosive device Friday, shortly before a Northwest flight from Amsterdam, Netherlands, made its landing in Detroit, Michigan.
With the aid of the cabin crew, another passenger quickly helped subdue and isolate Abdulmutallab, passenger Syed Jafry told CNN.
Abdulmutallab, was placed in custody and is being treated for second- and third-degree burns on his thighs, according to federal law enforcement and airline security sources.
The sources told CNN that the suspect flew into Schiphol Airport in Amsterdam on a KLM flight from Lagos, Nigeria, and is not believed to be on any "no fly" list, although his name does appear in a U.S. database of people with suspect connections. He did not undergo secondary security screening in Amsterdam, an administration official said.
The administration official said there was no evidence that Abdulmutallab was a hard-core, trained member of al Qaeda.
Abdulmutallab, a Nigerian national, claimed to have extremist ties and said the explosive device "was acquired in Yemen along with instructions as to when it should be used," a federal security bulletin obtained by CNN said.
The remains of the device used are being sent to an FBI explosives lab in Quantico, Virginia, for analysis, security sources said.
U.S. President Barack Obama, who is spending the holidays in his home state of Hawaii, was briefed on the incident during a secure phone call with aides, and instructed in a subsequent discussion with security advisers "that all appropriate measures be taken to increase security for air travel," White House spokesman Bill Burton told CNN. The president made no changes to his schedule, Burton said.
The Department of Homeland Security issued a statement Friday saying that air passengers "may notice additional screening measures put into place to ensure the safety of the traveling public on domestic and international flights."
Passengers described the brief moments of panic on board, as screams erupted and flight attendants ran for fire extinguishers.
Jafry, who was sitting in seat 16G, said the plane was just beginning to descend when passengers heard a pop.
"Everybody got a little bit startled," he said. "After a few seconds or so ... there was ... kind of a flamish light and there was fire" and people around the immediate area began to panic.
One woman told CNN affiliate WDIV that a man threw a blanket over Abdulmutallab's legs to help put out the small fire.
"It was terrifying," Richelle Keepman said. "I think we all thought we weren't going to land, we weren't going to make it."
Passenger Elias Fawaz told WDIV that the explosion sounded "like a balloon being popped" and said he could smell smoke.
Jafry said the incident was under control within minutes, crediting the crew and nearby passengers for the rapid response.
One person was taken to the University of Michigan Medical Center in Ann Arbor, hospital spokeswoman Tracy Justice said.
"All passengers have deplaned and out of an abundance of caution, the plane was moved to a remote area," where the plane and baggage were rescreened, the Transportation Security Administration said in a statement. Passengers were interviewed by law enforcement authorities before being allowed to leave the airport.
No other suspicious materials were found on the plane or in luggage, the law enforcement and airline security sources said. The suspect had only carry-on luggage.
Another passenger on the Northwest flight transferred from the same KLM flight in Amsterdam but officials found no connection between the two, the sources said.
The plane, an Airbus 330, landed shortly before noon ET. It was carrying 278 passengers.
Delta is the parent company of Northwest.
CNN's Mike Brooks, Jeanne Meserve, Kevin Bohn, Elise Labott, Ed Henry and Rachel Streitfeld contributed to this report.