MOSCOW, Oct. 17 (Xinhua) -- Three people were injured, and five others remain trapped after an explosion at the Avangard industrial plant in the western Russian city of Sterlitamak, local authorities said Friday.

The incident took place in the plant's nitro unit workshop, causing serious damage to the building, the city administration said on social media.

The factory employees have been evacuated, and emergency services and law enforcement officers are working at the scene, authorities said, adding that the injured were taken to a local hospital.

The cause of the explosion is currently under investigation, the administration added. ■