Several shot in Tennessee grocery store

A woman and child rest outside the supermarket crime scene

Police in the US state of Tennessee say that one person has been killed in a mass shooting at a grocery store, and 12 other people have been wounded.

The attack took place in Collierville on Thursday afternoon about 35 miles (56 km) east of the city of Memphis.

Police from neighbouring districts have arrived at the Kroger grocery store to assist in the investigation.

The gunman, who is male, died at the scene from a suspected self-inflicted gunshot wound.

"It breaks my heart to have to stand before you today," said Collierville Police Chief Dale Lane in a news conference after the shooting. "It's the most horrific event that's occurred in Collierville history."

A vehicle believed to belong to shooter is still in the car park, Chief Lane said. Investigators are awaiting more equipment in order to safely inspect the vehicle, "as well as some property that's on him," he said, referring to the killer.

Some of the twelve wounded have suffered "very serious injuries" he said, and one died at the scene.

Swat officers went "aisle to aisle, room to room, clearing, bringing employees out that were in hiding", he continued.

"We found people hiding in freezers, locked offices," Chief Lane added. "They did what they had trained to do - run, hide, fight." One employee was rescued by officers from the building's roof.

Police have not identified the attacker, or given any possible motive. They are checking reports that he may have been a Kroger employee.

Glenda McDonald, who works in the Kroger's flower department, told USA Today that she "just ran out the door" as soon as she heard the first gunshot.

"I left my purse, my keys, everything," she said, adding that she saw a grocery bagger and a customer get shot.

Multiple ambulances and helicopters are on the scene to transport the wounded to a nearby hospital.

The active shooter alert triggered a brief lockdown at the nearby Collierville High School. The lockdown has since been lifted.

This is not the first mass shooting at a grocery store in the US this year. In March, a man attacked people at a supermarket in Boulder, Colorado, killing 10 people including a police officer.

Tennessee was one of several states earlier this year to loosen restrictions on gun purchases. The newest rule, signed by the Republican governor, allows most adults over 21 to carry handguns without going through a state background check.