(Bloomberg) — The main search and rescue effort has been completed at the site where a China Eastern Airlines Corp. jet crashed last week, killing all 132 passengers and crew.

More than 49,000 pieces of wreckage were found during the search, Zhang Zhiwen, a senior official of the Guangxi autonomous regional government, said at a briefing Thursday in Wuzhou, near where the Boeing Co. 737-800 NG jet nosedived into a hillside on March 21. Officials said earlier in the week that DNA matching for everyone on the aircraft had been completed and all individuals identified.

Investigators will try to piece together the plane’s final moments from images reviewing trajectory, altitude, the force of impact and air-traffic data. A preliminary report will be produced within 30 days of the crash, but won’t include any conclusions as to its cause. The two black boxes have already been recovered and sent to Beijing for analysis.

Read more: Black Boxes May Unlock Secrets of China Jet’s Mystery Plunge

Countries leading an aircraft accident investigation must produce a preliminary report within 30 days of the incident, according to United Nations standards governing the aviation industry. A full report is expected within 12 months.

Flight MU5735 from Kunming was cruising at about 29,000 feet (8,840 meters) and some 100 miles from its destination in Guangzhou, southern China, when it suddenly went into a steep descent. Over the next 1 minute and 35 seconds the plane lost altitude in a near vertical dive, which took it almost to the speed of sound.

The plane briefly halted its descent for about 10 seconds, and climbed a little, before plummeting again and slamming into a hillside.

Some 34,000 rescue workers and staff were involved in the search. Officials said Thursday’s briefing would be the last on the crash to be held in Wuzhou.

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