Updated 11am with death toll.

A gunman shot and killed six people in a Walmart store in the US state of Virginia, police and city officials said, adding that the shooter too is dead.

"We were able to find multiple fatalities and multiple injured parties," Chesapeake Police Department officer Leo Kosinski told reporters at the scene, saying rapid response officers entered the store "immediately" as they arrived. 

"We believe it is a single shooter and that single shooter is deceased at this time," he added.

News footage showed a major police presence at the scene, with Kosinski saying several officers and investigators were combing through the store and securing the area.

CBS affiliate WUSA said police said they believed no more than 10 people were killed.

Virginia state Senator Louise Lucas, who represents the region, said she was "absolutely heartbroken that America's latest mass shooting took place in a Walmart in my district in Chesapeake, Virginia tonight."

"I will not rest until we find the solutions to end this gun violence epidemic in our country that has taken so many lives," she said on Twitter.