LANZHOU -- Three people have been killed and four injured when a crane toppled over while dealing with a train collision in northwest China's Gansu Province.

The dead, all staff of the Lanzhou Railway Bureau, were helping deal with the accident when the crane fell at about 5:00 pm on Tuesday, their relatives told Xinhua on Thursday.

A crane moving an oil tank that dropped from a cargo train crashed into the seven people. The four injured are in hospital.

Liang Weiping, one of the dead, and more than 100 workers rushed to deal with the collision in Shandan county on Monday night, according to Gong Yongjie, Liang's brother-in-law.

The cargo train numbered 85209 rolled backwards and hit the N857 passenger train. Nine carriages of the cargo train derailed, while the passenger train stayed on the rails, according to the Lanzhou Railway Bureau. No casualties were reported from the rail accident,

The accident has resulted in delays on some services.

The passenger train has arrived its destination of Dunhuang at 8:13 pm on Tuesday.