Turkey's showcase express train derailed Thursday in the northwest, killing at least 36 people and injuring about 60 after critics warned the old tracks along the Istanbul-Ankara (search) line could not handle the new high-speed cars.

At least four cars overturned near the small, rural village of Mekece, with most of the damage in two cars that crashed into each other. Bodies lay near the tracks as people climbed on the overturned cars looking for survivors. Darkness hampered rescue operations, with soldiers searching the wreckage and treating the injured by flashlight.

"The train was a little fast going around the curves," said injured passenger Namik Kemal Ozden, lying in his hospital bed with his face bandaged. "There were vibrations. My cousin was sitting next to me, we hugged each other. The windows broke and we fell to one side. We could only understand what happened once we got out."

It was not immediately known what caused the train to derail about halfway to its destination in the capital. But there was opposition when the line started operating June 4, with critics saying the tracks too old for the new trains.

The crash marked a setback to Turkey's efforts to modernize its outdated rail services and an embarrassment for the government of Prime Minister Recep Tayyip Erdogan (search), who had launched the high-speed line with gala celebrations.

There were conflicting reports of casualties, with the government crisis center, health ministry and transportation ministry earlier saying that between 128 and 139 people were killed. The agencies lowered the toll late Thursday without any official explanation.

"A mistake was made in the death and injury toll because of the contradictory information that reached us," said Ayhan Cevik, mayor of the nearby town of Bilecik. "According to the latest information we have, 36 people were killed in the accident and 60 were injured."

Authorities said they were not ruling out sabotage.

"We are assessing every possibility," said Muammer Turker, heading the crisis center in Sakarya. He said the train was carrying 234 passengers and nine railway employees.

When it derailed, the train would have been traveling at a normal speed, because the tracks near Mekece were not geared to carry high-speed cars, state railway authority deputy head Ali Kemal Ergulec said. It was not immediately known how fast the train was going when it derailed 113 miles away from Istanbul.

At the scene, rescue workers combed through the debris, looking for survivors. Paramilitary soldiers were carrying luggage from the debris and piling it on the side of the road.

"There were bodies lying all over the place," said Hikmet Feridun Turan, the major of nearby Pamukova and one of the first people to reach the site. "Body pieces. Heads lying on the ground. I don't want anyone to ever see anything like that."

The crash occurred at 7:45 p.m. By midnight, most of the rescue efforts were winding down.

Erdogan canceled a trip to Bosnia (search) and traveled to the area by helicopter. The prime minister said authorities would likely make an announcement on the cause of the crash Friday.

Oguz Dizer, a journalist traveling in the area, told NTV television he saw several bodies lying near the tracks.

"The scene is one of carnage," Dizer said. "There are people lying all over the place."

Suleyman Karaman, the head of Turkey's railway authority, said a team had been sent to the area to try and determine the cause of the crash. He quoted the conductor as saying the train was traveling at a normal speed and that he "could not understand what had gone wrong."