Five people were killed and four more injured when a boiler in a leather-making factory of Wenzhou, a coastal city in east China's Zhejiang Province, suddenly went off late on Sunday.

The explosion took placed around 9 p.m. at Taihao Leather-Making Factory in Yangyi Township of Wenzhou, and the casualties were caused as the blast toppled parts of the factory workshops and adjacent small shops built outside the factory compound, local police sources said.

It is known that the boiler was produced in 2002 by Quzhou Boilers Factory, also in Zhejiang Province, and passed a quality appraisal by the local quality inspection authority on May 9 this year.

The cause of the accident is being investigated.