An explosion ripped through a fireworks factory in Central China's Henan province Monday, leaving seven dead and 12 injured, local authorities said.

The explosion occurred at about 10:30 am at the Dongtun Fireworks Factory in Huaiyang county, the county publicity department said in a press release.

Five workers were killed at the scene and two died after emergency medical treatment failed. Another twelve injured are still under emergency treatment.

At the time of the blast, the workers were being involved in illegal production as the factory had been ordered to suspend production since its production license expired, according to the statement.

The factory owner's family have been held by police and the owner was already on its way home from a business trip.

The county authorities have ordered all local fireworks factories to suspend production to fix safety loopholes.

An investigation into the cause of the explosion is under way.