Turkey's state-run agency says a bus in Istanbul has veered out of its lane and crashed into oncoming traffic, causing a number of injuries.

Anadolu Agency said the accident occurred in the city's Acibadem district during morning rush hour on Friday. The bus slammed into another bus and several other vehicles on a main road.

Television footage showed at least three vehicles crushed beneath the weight of the bus.

The cause of the accident was not immediately known. The private Dogan news agency said there were unconfirmed reports that a fight broke out between the bus driver and a passenger.