An attempted terrorist attack on a Christmas Day flight began with a pop and a puff of smoke — sending passengers scrambling to subdue a man who claimed to be acting on orders from al-Qaida, officials and travelers said.

The commotion began as Northwest Airlines Flight 253, carrying 278 passengers and 11 crew members from Amsterdam, prepared to land in Detroit. Travelers said they smelled smoke, saw a glow, and heard what sounded like firecrackers. At least one person climbed over others and jumped on the man.

“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.”

Smith said one 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.

Afterward, the suspect was taken to a front-row seat with his pants cut off and his legs burned. Multiple law enforcement officials also said the man appeared badly burned on his legs, indicating the explosive was strapped there. The components were apparently mixed in-flight and included a powdery substance, multiple law enforcement and counterterrorism officials said.