Over-crowding could be to blame for the deaths of 92 people in the Xingxing coal mine explosion in China on Saturday, according to reports.
Nearly 500 miners were working underground when the gas explosion at the coal mine took place, trapping many inside.
The Xingxing mine is located in the frigid rust belt city of Hegang in Heilongjiang province in north-east China.
It is also believed inadequate ventilation and excessively big coal faces could have contributed to the blast, according to reports by AFP.
Rescuers are still searching for four missing people they say were near the centre of the explosion.
Officials said preliminary investigation suggested poor management at the mine, and owner of the mine Heilongjiang Longmay Mining Holding Group official Qi Weiping admitted that there were shortcomings with health and safety.