Emergency crews in Brazil on Saturday began removing the remains of the victims of a plane crash that killed all 62 people on board.

Authorities are baffled as to why the ATR 72-500 twin-engine turboprop plane went down a day earlier in a residential area of Vinhedo, a city some 80 kilometers (50 miles) northwest of Sao Paulo.

Video footage posted to social media showed the Voepass plane — bound for Sao Paolo from Cascavel, in the state of Parana — in a flat spin before hitting the ground. No injuries were reported on the ground.

What's the latest on the recovery effort?

At least 31 bodies had been recovered by 1 p.m. (1600 GMT/UTC) on Saturday, the Sao Paulo state government said, and were being moved to Sao Paulo's police morgue. The airline has previously said 61 people were on board, a figure it later corrected.

Dario Pacheco, the mayor of Vinhedo, said the bodies of the pilot and co-pilot were identified. 

Authorities said they were using seat assignments, physical characteristics, documents and belongings such as cell phones to identify the victims.

Victims' relatives were being taken to Sao Paulo to provide DNA samples to aid in the identification of the remains.

Voepass said four people with dual citizenship were among the victims, three Venezuelans and one Portuguese woman.

Brazil's airforce said the cockpit voice recorder and the flight data recorder were recovered and would be examined as soon as possible.

What happened to the plane?

Authorities said the aircraft was flying normally until 1:21 p.m. local time on Friday when it stopped responding to calls. Radar contact was lost at 1:22 p.m.

Pilots did not report an emergency or adverse weather conditions, Brazil's airforce said.

Data from Flightradar 24 suggested the plane — which had been in operation since 2010 — descended almost 4,000 meters (about 13,100 feet) in less than a minute.

Voepass's operations director, Marcel Moura, said the plane had undergone routine maintenance the night before the accident and that "no technical problems" were found.

Some experts think ice may have formed on the wings. A warning over possible ice formation was in place for the location of the crash, according to local media.

"We can see a plane with loss of support, no horizontal speed. In this flat spin condition, there's no way to reclaim control of the plane," Brazilian aviation expert Lito Sousa told the Associated Press.

Brazil's Federal Police has begun an investigation. The airforce will also hold a criminal probe, airports minister Costa Filho said.

The plane's builder, ATR, a joint subsidiary of European giant Airbus and of Italy's Leonardo, said its experts will assist in the investigation.

mm/sms (AFP, AP, dpa, Reuters)