ANKARA, Turkey (AP) — A bus traveling between cities in Turkey swerved off a highway and slammed into an overpass pillar on Friday, killing nine people on board, an official said. At least 26 other people were injured.

The crash occurred near the town of Polatli, some 80 kilometers (50 miles) from the capital, Ankara, Gov. Vasip Sahin told HaberTurk television station.

The bus was traveling from the city of Izmir in western Turkey to Agri in the east of the country, he said.

A deputy chief prosecutor was assigned to oversee an investigation into the cause of the crash, which led to the closure of one side of the highway, the state-run Anadolu Agency reported.

Sahin told reporters at scene of the crash that there were no skid marks on the road, suggesting the driver might have dozed off.

There was no information on the conditions of the injured passengers, who were taken to hospitals in Polatli and Ankara.

Images from the scene showed that the pillar sliced through the front half of the bus, with luggage and other belongings scattered in the twisted wreckage.