Beijing ? Aviation officials at a relatively new airport in northeast China searched through debris today for clues to why a passenger jet crashed and burned while trying to land on a fog-shrouded runway, killing 42 people and injuring 54 others.

The Henan Airlines plane with 91 passengers and five crew crashed late Tuesday in a grassy area near the Lindu airport on the outskirts of Yichun. Five of those onboard were children, the Civil Aviation Administration of China said, and at least one, an 8-year-old boy, survived.

It was China’s first major commercial air disaster in nearly six years. The plane’s black box was recovered, Xinhua reported, but it is still not known what caused the accident.

The newly built Yichun airport sits in a forested valley and has operated for a year, and concerns about the safety of night landings there had been raised by at least one major airline.

China Southern Airlines decided last August to avoid night flights in and out of Yichun, switching its daily flight from Harbin to the daytime.