The death toll from an explosion at a fireworks factory in northeast China's Heilongjiang Province last month has risen to 33.

An explosion ripped through the fireworks factory in the Wumahe District of Yichun City on Aug. 16.

Some 153 were injured in the accident and three people are still missing, Gao Weidong, vice director of Yichun's publicity department, said.

A preliminary investigation showed the plant was illegally producing fireworks, as the local work safety department canceled its production permit in June.

The State Council is heading an investigation into the accident.