A trapped university lecturer was pulled to safety from his fiercely burning car after hitting a pickup truck on elevated Boromratchonnanee Road in Bangkok Noi district late on Wednesday morning.

Police said Ratthakan Komolrat's black Nissan Teana ran into the back of a blue Isuzu D-Max pickup on the outbound side of the elevated road above Chao Phraya Hospital about 10.45am.

The car then caught fire. Mr Ratthakan was trapped inside, his legs stuck under the steering wheel and unable to open the car door.

Pol Sen Sgt Maj Wuthichai Paengsakol, from a local police station, and Pol Capt Saranpong Onsing, a highway officer from Nakhon Pathom province, both rushed to help as the flames intensified.

Pol Capt Saranpong was passing by on the other side of the road on his way to arrange a royal motorcade in Bangkok.

Using a hammer provided by a passer-by, they broke the driver's side window and pulled the injured man out of the car just before it was engulfed in flames.

Mr Ratthakan, 40, a lecturer at Mahidol University, escaped with cuts to his head and arms. The driver of the pickup truck he ran into suffered a cut on his head. They were both treated at Chao Phraya Hospital.