SHIJIAZHUANG - The death toll in a bus-truck collision in Hebei province has risen to 18 after a critically injured person died in hospital, local authorities said Sunday.

The accident happened at around 5 a.m. when an Iveco bus with 34 migrant workers onboard rear-ended a parked semi-trailer truck in Shangyi County.

Seventeen people in the bus were died at the site, with the rest of its passengers injured and rushed to hospital.

One of the seriously injured died later in hospital.

An initial investigation into the cause of the accident revealed that overloading of the 17-seat-bus, it being driven at a high speed and the driver being unqualified were to blame for the collision.

Foggy weather and the fact that the parked truck did not have its hazard lights on also contributed to the accident, according to the provincial public security department.

The overloaded Iveco bus was not registered, according to the police.