BEIJING, (Reuters) – After discovering two black boxes in a crash China Eastern plane, rescue crews now seek more debris and video footage from nearby areas. Eyewitness accounts are also being sought, a representative of China’s aviation regulator stated on Monday.

The Boeing (NYSE) 737-885 aircraft that was flying Flight MU5735 crashed into a mountainside on Monday. It killed all 132 passengers and caused the worst aviation accident in China in over 28 years.

Zhu Tao (head of Civil Aviation Administration of China’s Aviation Safety Office) stated at a press conference that “large-scale air accident investigations that only rely upon data from the black boxes often fail to tell the entire truth of the incident.”

Zhu stated that while we are examining the data in the black boxes, they’re trying to gather as much debris from the planes as possible as well as more footage and witnesses accounts.

The second black box, the flight data recorder, was found by rescue crews from the aircraft’s wreckage on Sunday.

Zheng Xi of Guangxi Fire & Rescue Corp said that more than 15,000 emergency and search personnel have been dispatched so far to assist in the rescue operations. Additionally, over 370,000 sq. meters of debris from planes have been discovered.

Zheng stated that deep excavations were being conducted using earthmoving equipment in an effort to find more of the personal items of passengers.