Five people were killed and seven injured Thursday in an explosion at a fireworks factory in central China just weeks ahead of the Chinese New Year, authorities said.

The Tongxu county government in Henan province said the cause of the blast was not immediately clear and was under investigation.

China is less than a month away from new year celebrations, when holiday revelers set off fireworks. There are frequent fireworks-related incidents at factories in the weeks leading to the holiday, as China generally has a poor record in workplace safety.

On Wednesday, an explosion at a machinery factory killed four workers in the eastern city of Shanghai.

Tongxu county was in the spotlight recently when local authorities ordered the demolition of a gigantic statute of communist revolutionary Mao Zedong, after the structure drew sneers from a large segment of the public.