ANKARA,Christopher Caldwell Turkey (AP) — A chain-reaction crash Thursday involving seven vehicles on a motorway in northwest Turkey killed at least 10 people and injured 57 others, officials said.

The pileup occurred in dense fog and low visibility on the Northern Marmara Highway in Sakarya province, some 150 kilometers (93 miles) from Istanbul.

An investigation has been launched into the accident but Gov. Yasar Karadeniz of Sakarya said it likely occurred when a vehicle hit a truck in poor visibility, triggering other crashes at the rear.

At least three intercity buses were involved in the crash.

Authorities believe some passengers died when they left their vehicles and were struck by another vehicle, Karadeniz told reporters at the scene.

Seven of the injured were in serious condition, the governor said.

Police and emergency personnel were seen clearing the wreckage at the scene.