At least three students were killed in a laboratory blast at a Beijing university on Wednesday, the city’s fire department said.

According to the Beijing Fire Department; “There was an explosion at the experimental site during a scientific research experiment” on wastewater treatment in the Environmental Engineering Laboratory.

“The accident caused three students to die,” it added in a statement posted on its social media account.

The incident happened just after 9:30am (0130 GMT) at the Beijing Jiaotong University in the western part of the city.

Some 30 fire engines were sent to the scene, and took nearly an hour to get the blaze under control. Local authorities are launching an investigation into the cause of the incident.