Beijing, China (CNN) -- Investigators were trying to determine Wednesday what caused China's first fatal passenger plane crash in almost six years.
A Henan Airlines flight with 96 people on board overshot a runway and crashed Tuesday night in the Yichun area of northern China, state media said. The plane broke into two pieces and burst into flames.
On Wednesday, the government downgraded the death toll from the crash from 43 to 42 after a body that was torn apart was discovered to have been counted twice, according to the state-run Xinhua news agency. Fifty-four people survived.
Five children injured in the crash were in critical condition, said Xinhua, citing doctors in Harbin, the capital of Heilongjiang province, where they had been transferred. Another 10 people were severely injured, it said.
"The coming 48 hours are the dangerous period," said Wang Yongchen, deputy head of the No. 1 Hospital affiliated with Harbin Medical University.
Four of the children suffered heavy respiratory tract burns, said Wang.
The investigators' initial focus was to find the flight data recorder -- commonly known as the "black box" -- that might yield clues as to what caused the Brazilian-made Embraer 190 jet to crash land in heavy fog on a patch of grass about 1.5 kilometers (0.9 miles) from the runway.
The black box was found on the ground Wednesday morning, Xinhua said.
Some passengers were thrown from the plane upon impact, according Xinhua, which cited the head of the publicity department of the Yichun city committee of the Communist Party of China.
Chinese Vice Premier Zhang Dejiang led a team of transportation, health, work safety and security officials to Yichun after the crash, state media said.
Two survivors told local television that the plane shook violently before it crashed and that thick smoke entered the cabin soon after impact. They said passengers were unable to open emergency exits after the wreck; survivors escaped through cracks in the fuselage.
The plane was carrying 91 passengers, including five children, and five crew members when it crashed at 9:36 p.m. (9:36 a.m. ET), according to Xinhua, which cited a source with the Civil Aviation Administration of China.
The Henan Airlines flight had taken off from Harbin on the 360-kilometer (225-mile) flight to Lindu Airport, about 9 kilometers (5.6 miles) from downtown Yichun, a city of about 1 million residents near the Russian border, Xinhua said.
A Yichun vice-mayor told Xinhua that most of those taken to hospitals did not have life-threatening injuries.
China's last fatal passenger airline accident occurred in November 2004, when a China Eastern commuter jet took off in frigid Inner Mongolia without de-icing and crashed shortly afterward into a nearby park, killing 55 people.
CNN's Steven Jiang contributed to this report.