Three people have been killed in a shooting at a Rite Aid distribution centre in north east Maryland, officials said.

A law enforcement official with knowledge of the shooting stressed that the number of dead is based on preliminary information.

A suspect was taken into custody and was in critical condition, Harford County Sheriff Jeffrey Gahler told a news conference.

Maryland Shooting
Authorities respond tothe shooting (Jerry Jackson/AP)

It appears there was only one weapon, a handgun, that was used and there were no shots fired by responding law enforcement officers, Mr Gahler said.

Mr Gahler also said multiple people had been killed and wounded in the shooting, without giving any other details on casualties.

A Baltimore hospital said it had received four patients with gunshot wounds from the shooting. Johns Hopkins Bayview Medical Centre spokeswoman Monica Stone said that she was unable to provide details about the patients’ conditions.

Mr Gahler said the call about shots fired came in from the Rite Aid distribution centre at about 9:06am and deputies and other officers were on the scene in just over five minutes.

“We are so preliminary in this investigation,” Mr Gahler said. “It’s so important that we deal in facts.”

He said authorities do not want to “make it worse” for the families involved by giving out incorrect information.

At a nearby fire station, family members were waiting to be reunited with loved ones. Police blocked off the road outside but were waving in cars driven by people who said they were there to meet up with people who were at the distribution centre.

Maryland Shooting
Authorities respond to the shooting (Jerry Jackson/AP)

The attack came nearly three months after a man armed with a shotgun attacked a newspaper office in Annapolis, Maryland, killing five staff members.

Authorities accused Jarrod W Ramos of attacking The Capital Gazette because of a longstanding grudge against the paper.

The FBI described the Aberdeen incident as an “active shooter situation” and said its Baltimore field office was assisting.

In a tweet, Maryland Gov Larry Hogan said his office is monitoring the situation in Aberdeen and that the state stands ready to offer any support.

Susan Henderson, spokesman for the store chain Rite Aid, said the shooting happened on the campus of a company distribution centre in Aberdeen. She described it as a support facility adjacent to a larger building.

Harford County Executive Barry Glassman said that unfortunately, incidents like this are “becoming a too-often occurrence not only in Harford County but in the country”.