A baseball-sized, military tear gas grenade exploded in the basement of a Sacramento-area Sears store after a security officer pulled it from his desk. The grenade spewed chemical fumes into the store, injuring at least 44 people. The victims, all suffering minor injuries from chemical irritation, were treated at nearby hospitals, sheriff's deputies said. One witness said the explosive device, apparently an old military training grenade that had been confiscated several months ago by store guards, blew up in the security office after supervising officer Will Updegraff snagged it on something. He suffered facial cuts.