DETROIT -- A Northwest Airlines passenger from Nigeria, who said he was acting on al-Qaida's instructions, set off an explosive device Friday in a failed terrorist attack on the plane as it was landing in Detroit, federal officials said.
Flight 253 with 278 passengers aboard was 20 minutes from the airport when it sounded like a firecracker had exploded, witnesses said. One passenger jumped over others and tried to subdue the man. Shortly afterward, the suspect was taken to a front row seat with his pants cut off and his legs burned.
The White House said it believed it was an attempted act of terrorism and stricter security measures were quickly imposed on airline travel, but were not specified.
Law enforcement officials identified the suspect as Umar Farouk Abdul Mutallab. Others had slightly different spellings.
One law enforcement source said the man claimed to have been instructed by al-Qaida to detonate the plane over U.S. soil.
''It sounded like a firecracker in a pillowcase,'' said Peter Smith, a passenger from the Netherlands. ''First there was a pop, and then (there) was smoke.''
At least one passenger acted heroically.
Smith said the passenger, sitting opposite the man, climbed over passengers, went across the aisle and tried to restrain the man. The heroic passenger appeared to have been burned.
The incident was reminiscent of convicted shoe bomber Richard Reid, who tried to destroy a trans-Atlantic flight in 2001 with explosives hidden in his shoes, but was subdued by other passengers. Reid is serving a life sentence.
Rep. Peter King, R-N.Y., ranking GOP member of the House Homeland Security Committee, said the flight began in Nigeria and went through Amsterdam en route to Detroit.
A statement Delta, which acquired Northwest, said, ''Upon approach to Detroit, a passenger caused a disturbance onboard Northwest Airlines Flight 253. The passenger was subdued immediately and the crew requested that law enforcement meet the flight upon arrival.
''The flight, operated by Northwest using an Airbus 330-300 aircraft with 278 passengers onboard, landed safely. The passenger was taken into custody and questioned by law enforcement authorities.''
The FBI and the Homeland Security Department issued an intelligence note on Nov. 20 about the threat picture for the 2009 holiday season from Thanksgiving through Jan. 1. At the time, intelligence officials said they had no specific information about attack plans by al-Qaida or other terrorist groups. The intelligence note was obtained by The Associated Press.
President Barack Obama was notified of the incident and discussed it with security officials, the White House said. It said he is monitoring the situation and receiving regular updates from his vacation spot in Hawaii.
There was nothing out of the ordinary about Flight 253 on Friday until it was on final approach to Detroit, said Federal Aviation Administration spokeswoman Elizabeth Isham Cory. That is when the pilot declared an emergency and landed without incident shortly thereafter, Cory said. The plane landed at 12:51 p.m.
One U.S. intelligence official said the explosive device was a mix of powder and liquid. It failed when the passenger tried to detonate it.
The passenger was being questioned Friday evening. An intelligence source said the Nigerian passenger was being held and treated in an Ann Arbor, Mich., hospital.
All the sources spoke on condition of anonymity because the investigation was continuing.
The official said an official determination of a terrorist act would have to come from the attorney general. The official added that additional security measures were being taken without raising the airline threat level, but declined to describe them.
The White House was coordinating briefings for the president through the Homeland Security Department, the Transportation Security Administration and the FBI.
A law enforcement source said the explosives may have been strapped to the man's body but investigators weren't immediately certain, partly because of the struggle with other passengers.
One passenger from the flight was taken to the University of Michigan Medical Center in Ann Arbor, hospital spokeswoman Tracy Justice said. She didn't know the person's condition, or whether the person was a man or woman. She referred all inquiries to the FBI.
Passenger Syed Jafri, a U.S. citizen who had flown from the United Arab Emirates, said the incident occurred during the plane's descent. Jafri said he was seated three rows behind the passenger and said he saw a glow, and noticed a smoke smell. Then, he said, ''a young man behind me jumped on him.''
''Next thing you know, there was a lot of panic,'' he said.
Rich Griffith, a passenger from Pontiac, said he was seated too far in the back to see what had happened. But he said he didn't mind being detained on the plane for several hours. ''It's frustrating if you don't want to keep your country safe,'' he said. ''We can't have what's going on everywhere else happening here.''
J.P. Karas, 55, of Wyandotte, Mich., said he was driving down a road near the airport and saw a Delta jet at the end of the runway, surrounded by police cars, an ambulance, a bus and some TV trucks.
''I don't ever recall seeing a plane on that runway ever before and I pass by there frequently,'' he said.
Karas said it was difficult to tell what was going on, but it looked like the front wheel was off the runway.
''We encourage those with future travel plans to stay in touch with their airline and to visit www.tsa.gov for updates,'' Homeland Security Department said in a statement.
Homeland Security Secretary Janet Napolitano has been briefed on the incident and is closely monitoring the situation.
The department encouraged travelers to be observant and aware of their surroundings and report any suspicious behavior to law enforcement officials.