SHIJIAZHUANG - At least 27 people were injured in an explosion in a six-storey residential building on Saturday afternoon in Baoding city, north China's Hebei Province, local government said.

Among them, three were in critical condition, said a spokesman with the city government.

All of them were sent to hospital for treatment, said the spokesman.

Part of the building collapsed after the blast happened at around 3 p.m. at the Yaoheningyuan Residential Community in Baoding.

Witnesses said heavy smoke broke out following the explosion, which shattered window glass of buildings 200 meters away.

Rescue work is still under way and the cause of the accident is being investigated.