At least one victim died and at least 12 others were injured after a gunman opened fire in a grocery store near Memphis in the US state of Tennessee on Thursday, according to police.

The shooter died, possibly of a self-inflicted gunshot wound, Collierville Police Chief Dale Lane told reporters at a press conference. The suspect's vehicle is in the Kroger Supermarket parking lot, and police are waiting on specialized equipment to carry out a search.

Initially 13 people were reported to have been injured, but Lane said the number is at least 12, with one confirmed fatality.

Lane said the status and number of the victims "is probably going to change," describing some of the injuries that have been confirmed as "very serious." He cautioned that additional people may have been injured with at least one person taking themself to a local hospital.

"This scene is horrific. I've been involved in this for 34 years and never seen anything like it," he said. “We found people hiding in freezers. They were doing what they had been trained to do: run, hide, fight.”

Additional updates are expected during a press conference scheduled later Thursday evening./aa