The public is demanding more information from the railway authority on why two passengers trains collided in central China on Monday, killing three and injuring 63.

A railway official said on Tuesday that one of the trains suffered "brake failure" before running into another train in Chenzhou, Hunan province, but did not elaborate why.

The comment soon raised doubts with the public. Some net users said a train is usually equipped with back-up brakes for emergencies.