(Reuters) – One person was killed and at least 12 were injured when a lone gunman opened fire on Thursday at a supermarket in suburban Memphis, Tennessee, before the suspect was found dead from an apparently self-inflicted gunshot wound, the police chief said.

Law enforcement officers swarmed to the scene just after the shooting unfolded at a Kroger grocery store in Collierville, Tennessee, and began helping victims and others found hiding inside the supermarket, chief Dale Lane told reporters.

“We found people hiding in freezers and in locked offices,” Lane said.

The gunman, who was believed to have acted alone, was found dead in a parking lot outside the store, Lane said. Local media reported the suspect’s body was discovered inside his vehicle.

“We are waiting for some special equipment to search that vehicle as well as the property that is on him,” Lane said about two hours after the shooting, which erupted at about 1:30 p.m. local time.

He called the gun violence “the most horrific event that has occurred in Collierville history.” The town is located about 30 miles (50 km) east of Memphis in southwestern Tennessee.

No immediate explanation for a possible motive was offered by authorities.

Lane said some of the surviving victims sustained “very serious” injuries. All were taken to area hospitals, he said.

(Reporting by Peter Szekely and Barbara Goldberg in New York; Writing and additional reporting by Steve Gorman in Los Angeles; Editing by Aurora Ellis and Sonya Hepinstall)