Multiple people were shot and killed inside a Walmart in Chesapeake, Va., on Tuesday night, the authorities said, the second high-profile mass shooting in the country in three days.

The shooter, whose name the authorities did not release, was found dead at the store, Leo Kosinski, a spokesman with the Chesapeake Police Department, said in a brief news conference.

Mr. Kosinski did not say exactly how many people had been fatally shot, but he said he believed it was “less than 10.”

The Police Department responded to a report of a shooting inside the Walmart at about 10:12 p.m., Mr. Kosinski said, about 45 minutes before the store was scheduled to close.

He added that when officers entered the store, they found “multiple fatalities and multiple injured” individuals.

Mr. Kosinski said investigators did not know if the shooter was an employee or whether he had died by suicide. He added that he did not believe any shots had been fired by police officers.

Walmart said in a statement early Wednesday morning that “we are shocked at this tragic event at our Chesapeake, Virginia, store.”

“We’re praying for those impacted, the community and our associates,” the company said. “We’re working closely with law enforcement, and we are focused on supporting our associates.”

“I mean it’s sad, you know we’re a couple days before the Thanksgiving holiday,” Mr. Kosinski said.

In a shooting over the weekend, five people were killed at an L.G.B.T.Q. club in Colorado Springs, Colo.

Earlier this month in Charlottesville, Va., three members of the University of Virginia football team were killed by a former football player, who opened fire in a garage, the authorities said.

Photos and videos from the scene of the Walmart shooting showed officers huddling around the entrance of the building on Sam’s Circle, with numerous police vehicles parked in the large lot of the store, which is off Battlefield Boulevard. A large inflatable Santa Claus stood outside the store.

Mr. Kosinski said that officers were searching for more victims inside the Walmart shortly after midnight on Wednesday.

He noted that the large store “had a lot of hiding spots” for shoppers who had possibly sought cover during the shooting.

“People could get scared, they could be hiding,” Mr. Kosinski said. “We want to make sure that everyone is accounted for.”

The authorities directed relatives of people affected by the shooting to the Chesapeake Conference Center. Local TV stations reported that a chaplain would be there.

The Walmart supercenter where the shooting occurred is one of several in southeastern Virginia. It includes a grocery store, a pharmacy, a bank, a bakery and a deli, among other businesses. Mr. Kosinski told reporters that the Walmart was “very, very large,” although he did not know the square footage.

Chesapeake, a few miles south of Norfolk, had a population of about a quarter of a million people last year, according to the United States Census Bureau. It is near Virginia’s Atlantic coast and the border with North Carolina.

Sen. Mike Warner of Virginia, a Democrat, said in a statement that he was “sickened by reports of yet another mass shooting.”

L. Louise Lucas, a Virginia state senator, said on Twitter that she was “absolutely heartbroken that America’s latest mass shooting took place in a Walmart in my district in Chesapeake.”

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