Mississippi ? A massive natural gas explosion leveled a clinic Saturday, injuring nine people and shattering windows at a nearby hospital, authorities and witnesses said.

The clinic, which contained four doctors’ offices, was gutted by the explosion and subsequent fire.

“Gas leaked into the sewer line and that’s how it got in the building,” Mayor Rayburn Waddell said.

Businesses more than 800 feet away reported windows being blown out and roof damage. Authorities said 35 windows were shattered at the county hospital and nursing home. No one in those buildings was injured.

Nine people were treated at Neshoba County Hospital, Police Chief Dickie Sistrunk said.