XINING - One person was killed and three others were seriously injured after an empty train hit a parked passenger train on the Qinghai-Tibet railway line in Northwest China's Qinghai province on Wednesday, local authorities said Thursday.

The collision happened at around 8:10 pm when the empty train, operated by Golmud East Railway Station, crashed into the No 7581 passenger train just outside the station.

A total of 52 people - 47 passengers and five train workers - were rushed to hospital for treatment or observation, said the Qinghai-Tibet Railway Company.

As of 8 am Thursday, a critically injured passenger, who was trapped between two carriages of the passenger train and later rescued, died in hospital.

Three other passengers with serious injuries are in stable condition, said the company.

Rescue efforts at the scene ended early Thursday. The cause of the collision is being investigated.