While acknowledging that multiple people had been shot and killed, the Harford County sheriff refused to provide a number as the investigation was in the "preliminary" stage. He shared the shooter used a handgun and was in custody.
At least three people have been killed on Thursday morning in a shooting at a Rite Aid distribution centre in northeast Maryland, officials said.
A law-enforcement official with knowledge of the shooting stressed that the number of dead is based on preliminary information. The official wasn't authorised to discuss details by name and spoke on condition of anonymity to The Associated Press.
A suspect was taken into custody and was in critical condition, Harford County Sheriff Jeffrey Gahler told a news conference.
It appears there was only one weapon, a handgun, that was used and there were no shots fired by responding law-enforcement officers, Gahler said. Gahler also said multiple people had been killed and wounded in the shooting, without giving any other details on casualties.
Gahler said the call about shots fired came in from the Rite Aid distribution centre at about 9:06 am local time and deputies and other officers were on the scene in just over five minutes.
"We are so preliminary in this investigation," Gahler said. "It's so important that we deal in facts." He said authorities don't want to "make it worse" for the families involved by giving out incorrect information.
Daughter of woman who works in Harford County, MD, warehouse attacked by mass shooter awoke to this message at 9:31 this morning. She hasn't heard from her mother since. pic.twitter.com/OWw8FoYyU9— Tony Pipitone (@TonyNBC6) September 20, 2018
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 Governor Larry Hogan said his office is monitoring the situation in Aberdeen and that the state stands ready to offer any support.
Susan Henderson, a spokesman for the drugstore 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."
TRT World's North America correspondent Jon Brain has more.
Wisconsin workplace shooting
Police say the gunman who was killed by officers after shooting four people at his Wisconsin workplace on Wednesday is a 43-year-old man who had been employed at WTS Paradigm, a software company, since April 2017.
Middleton Police Chief Chuck Foulke declined to identify the gunman during a news conference on Thursday, but he says the man had no criminal history and no prior contact with area law-enforcement officers.
Foulke says two men and one woman were seriously wounded in the attack and remain hospitalised.
The chief says the gunman arrived for work and sometime later opened fire on his colleagues. An autopsy by the Dane County Medical Examiner's Office is scheduled on Thursday.