Two trains collided head on in northwestern Turkey on Wednesday, killing at least four people, injuring 55 others and sending emergency crews in a frantic search for survivors.

Rescue workers in orange and blue jump suits, one holding a white body bag, climbed on top of a smashed locomotive that flipped over in the collision near the village of Tavsancil in Kocaeli province, some 50 miles east of Istanbul (search).

The accident happened after a train traveling from Ankara (search) to Istanbul ignored a signal and failed to stop at a junction, Cemal Yaman, an official of a local branch of the train workers' union told the Anatolia news agency. The other train was traveling from Istanbul to Adapazari, officials said.

"One of the trains passed a red light," Deputy Prime Minister Abdullah Gul said. "When the (engineer) noticed, he tried to reduce speed but unfortunately the accident occurred."

The train traveling from Ankara was carrying 153 passengers and nine crew members, the Anatolia news agency said.

Four passengers were killed and 55 people were injured in the crash, Gul said. Earlier, the mayor of Tavsancil said six people were killed and some 30 others were injured. There was no immediate explanation for the discrepancy.

Mahmut Yanmis, a survivor from the worst-hit car, told CNN-Turk television the accident happened after his train left Tavsancil station.

"I made my way through a broken window," said Yanmis, who had stitches on his head and scratches on his arms. "When went out of the car, I saw the decapitated body of a conductor trapped at the gate of the locomotive."

"I saw the passenger sitting next to me dead. Body pieces were scattered everywhere," he said.

Television footage showed firefighters climbing cars to rescue people. Others could be seen cutting through the side of wrecked cars.

The accident comes just weeks after a newly inaugurated high-speed train from Istanbul to Ankara derailed, killing 37 people — one of the worst train accidents in Turkey. Three days later, a passenger train slammed into a minibus at a railroad crossing in western Turkey, killing 15 people and injuring four others.

The train derailment — which occurred some 60 miles away from Wednesday's crash — was a major embarrassment to the government of Prime Minister Recep Tayyip Erdogan, who personally launched the train in June.

The government has launched three separate probes — by academics, a prosecutor and a team of foreign experts — into that accident.