The pilot of a small plane averted death twice in under five minutes on Sunday, first when he crash-landed onto railroad tracks, then when Los Angeles police rescued him just before a commuter train smashed into the aircraft.

Bodycam video showed the officers working furiously to disentangle the bloodied pilot from the cockpit of the crumpled Cessna 172.

"Go! Go! Go! Go! Go!" someone yelled as the officers dragged the man away seconds before the Metrolink train, its horn blaring, barrelled through the plane.

The plane crashed shortly after takeoff at 2.10pm from Whiteman Airport in the San Fernando Valley community of Pacoima, according to the Federal Aviation Administration. The timestamp on a police officer's body camera showed that the train hit the plane at 2.15pm.

The plane had landed on the tracks at a railroad crossing just blocks from the Los Angeles Police Department's Foothill Division station, and officers arrived at the crash scene almost immediately.

CBSN Los Angeles said four officers rescued the pilot and dragged him on to the footpath. The station identified them as Damien Castro, Christopher Aboyte, Robert Sherock and Sergeant Joseph Cavestany.

It was unclear how much time passed before authorities realised the plane was on the tracks, or exactly when police notified the railroad, but the officers realised there was no time to spare.

"I had requested Metrolink to cease all train activity, but apparently that didn't happen," Cavestany said.

The male pilot was the only person on board and was taken to a hospital for treatment, the Los Angeles Fire Department said. He was not identified and no other injuries were reported.

"Seeing what happened, I'm grateful to be alive. I'm grateful the pilot survived as well," Sherock said.

Metrolink subsequently halted train service and road traffic was detoured in the area about 32km northwest of downtown Los Angeles. The FAA and the National Transportation Safety Board will investigate. - AP