A woman armed with a handgun opened fire on Thursday at a Maryland distribution centre for the Rite Aid pharmacy chain, killing three people and wounding three others before she took her own life, the Harford County sheriff said.
The shooting unfolded shortly after the suspect, a temporary employee at the facility, reported for work at about 9am local time (2pm Irish time) at the warehouse in Perryman, Maryland, about 55km northeast of Baltimore, Sheriff Jeffrey Gahler said at a news conference.
The sheriff's office identified the assailant only as a 26-year-old woman whose last known address was in Baltimore County.
The sheriff said investigators had not yet determined a motive, but a law enforcement source said the shooting was believed to have been sparked by a work-related grievance.
The fact that the assailant was a woman was unusual as the overwhelming majority of mass shootings in the United States are committed by men.
Mr Gahler said the shooting began outside the warehouse and then moved inside. He said a total of seven people were hit by gunfire and that four, including the woman who opened fire, were killed. – Reuters