Seven people were killed by gunfire in a supermarket in Chesapeake, Virginia.
Among them was the alleged shooter, the administration of the east coast city said on Wednesday night, citing the police on Twitter.
According to media reports, at least five injured people were taken to hospitals.
Nothing was initially known about the background.
The incident happened two days before Thanksgiving, when many people were shopping for the US's all-important Thanksgiving holiday.
Police spokesman Leo Kosinski said at 10:12 p.m. police were alerted to a shooting at a Walmart Supercenter.
Upon entering the building, officials found "several dead and several injured."
It is a very big business, the search for other possible victims is still ongoing.
Dozens of police cars and ambulances could be seen in pictures and videos in front of the mall.
"It is sad.
We are a few days before Thanksgiving.
It's a bad time for everyone involved, especially the victims.
It's awful," Kosinski added.
"Thank God I was late," a night shift worker told local broadcaster WAVY TV.
"We are shocked by this tragic event," retail giant Walmart said in a statement.
The company works closely with the police.
Just over the weekend, five people were killed and 18 others injured in a shooting at a nightclub popular with gay, lesbian and trans people in Colorado.
The US has long struggled with massive levels of gun violence.
Firearms are often readily available in the country.
According to the latest data from the health authority CDC, around 20,000 people were shot in the USA in 2020 alone - more than 50 a day.
Chesapeake has around 250,000 inhabitants and is located on the east coast of the USA.