JINAN - A blast occurred at a chemical plant in East China's Shandong province on Saturday, but casualties remain unknown.

The blast occurred around 11 am at Yongxin Chemical Plant in Boxing county, located about 150 km northeast of the provincial capital Jinan, sources with the local government said.

A preliminary investigation failed to turn up casualties at the scene, the sources said, adding that firefighters have rushed to the site to carry out rescue work.

It was initially determined that a chimney exploded at the plant, which mainly handles petrochemical production.