CHESAPEAKE, Va. — A Walmart manager opened fire on fellow employees in the break room of a Virginia store, killing six people in the country’s second high-profile mass shooting in four days, police and witnesses said Wednesday.

The gunman, who apparently shot himself, was dead when officers found him, police said. There was no clear motive for the shooting, which also put four people in the hospital.

The store was busy just before the attack Tuesday night as people stocked up ahead of the Thanksgiving holiday, a shopper told a local TV station. ...