Multiple people were killed and wounded after a shooter opened fire in Harford County of Maryland in the United States on Thursday, the county’s sheriff said. The shooter, reportedly a woman, is in custody and in a critical condition in hospital. Authorities said they do not believe there is any further threat.

The number of people killed was at least three, reported AP, quoting an unidentified law enforcement official. This number was based on preliminary information, the official said.

The incident took place around 9 am local time (6.30 pm Indian time) near Aberdeen on the campus of a drugstore chain’s distribution centre, which employs close to 1,000 people. The Sheriff’s Office asked people to avoid the area and said that multiple law enforcement agencies were helping out in the operations.

“Police have arrived at the facility and we are cooperating fully with their investigation regarding this incident,” The New York Times quoted Susan Henderson, spokesperson for drugstore chain Rite Aid, as saying.

Many victims were taken to the Johns Hopkins Bayview Medical Center in Baltimore, said a hospital spokesperson.