A team investigating the Baotou air crash says, so far no evidence indicates the crash was caused by man-made factors. The team says the flight-data recorders, or black boxes, aboard the plane have not yet been found.

Early on Sunday, a passenger plane of the China Eastern Airlines crashed at the suburb of Baotou City in north China's Inner Mongolia Autonomous Region, seconds after it took off for the eastern China metropolis Shanghai, killing all 53 people aboard and one more on the ground.

More than 400 people, including local firefighters, police officers and medical workers have joined the rescue effort

Several hours after the tragedy, an investigative team led by the State Work Safety Administration and the General Administration of Civil Aviation of China arrived in Baotou to handle the case.