HANGZHOU, Oct. 30 -- Four people died and another four were injured after a blast hit a mould factory in east China's Zhejiang Province, said local authorities on Thursday.

The explosion occurred at around 8 a.m. Thursday at Zhejiang Jingruigong Mould Co., Ltd. in Huzhen Township, Jinyun County. Three workers were killed on the spot.

Among the five injured, one died in the hospital, one was in critical condition and three were in stable condition.

The cause of the accident is being investigated. The county government has ordered a work safety check-up for companies throughout the county.