LUCKNOW—At least 16 people were killed and another six injured in a suspected case of electrocution in the north Indian state of Uttarakhand on Wednesday morning, government officials said.

The incident took place inside a sewage treatment plant established in the Himalayan state’s Chamoli district as part of a flagship program of the federal government that focuses on conserving the river Ganga.

The deceased include a police officer and three personnel from the Home Guard, officials said, adding that the latter is suspected to have died as they attempted to rescue the police officer.

A magisterial inquiry has been launched into the incident.

“How the incident happened will only become clear after detailed inquiry but it seems, on the surface, to have happened due to electrocution,” said Himanshu Khurana, the district magistrate of the area.