Another violent weekend leaves U.S. on edge after shootings kill 8

A man firing a rifle killed shoppers at an Indiana mall’s food court. A gunfight at a Houston home killed four people.

A stand-up act by the comedian Craig Robinson in North Carolina didn’t even begin before club-goers fled from a man with a gun.

In Las Vegas, the specter of gunfire at the MGM Grand sent the crowded casino into pandemonium, with gamblers flipping over poker tables to shield themselves over a panic that started with a shattered glass door.