Three people were killed and one injured in a chemical plant blast early Thursday morning in north China's Inner Mongolia Autonomous Region, local safety authorities said.

The explosion happened at about 3:30 a.m. in CNSIC Jilantai Chlor-Alkali Chemical Plant in Alxa League. Three people died at the scene and one was rushed to a local hospital.

The chemical plant is a subsidiary of the China National Salt Industry Corporation (CNSIC).

Local safety authorities are investigating the cause of the blast.