JINAN, Aug. 11 -- The death toll in a multiple-vehicle accident in east China's Shandong Province on Thursday morning has risen by four to 10, local authorities said.

Another 20 were injured and of them, two were in critical conditions.

The pile-up happened in Boshan district, Zibo city, around 8:23 a.m. when a truck collided with two buses, a car and a motorcycle on a village road, the district government said.

An investigation into the cause of the accident is under way.