ANKARA (Reuters) – Five people, including one child, were killed and 15 others were wounded when a bus in northwestern Turkey caught fire on Friday, the province’s governor was quoted as saying, adding that the cause of the fire was not immediately clear.

The bus had departed from the northwestern province of Canakkale and caught fire on the highway in Balikesir en route to Ankara, Balikesir Governor Ersin Yazici was quoted as saying by broadcaster NTV. He said four of the injured passengers had been released from hospital and 11 were receiving treatment.

“The technical team has not finished its evaluation yet, so I can’t say it was caused by this or that, but findings show the fire started inside the bus,” Yazici said. “This is not an accident, it’s a fire that started inside the vehicle.”

Footage from the incident showed smoke billowing from the bus, which was parked on the highway, as firefighters sprayed water on the vehicle to put out the fire.