Three people were shot dead and another three were injured after an employee opened fire at a Rite Aid distribution center in Maryland on Thursday morning, law enforcement officials said.

The incident in Aberdeen, about 30 miles from Baltimore, ended when the shooter, Snochia Moseley, 26, shot herself in the head. She later died at the hospital.

Moseley, of Baltimore, was a temporary employee, who reported to work as usual around 8 a.m. and started shooting about an hour later. She began outside the Rite Aid facility then moved into the building, Harford County Sheriff Jeffrey R. Gahler said.

Two of the victims died at the scene, and one died at the hospital, according to police. The three additional victims who were wounded were hospitalized but were expected to survive.

Gahler said investigators are still working to determine a motive. He said he didn't know how well the victims and shooter knew each other, but they likely had some previous interaction because "it was not her first day."

The FBI office in Baltimore and special agents from the Bureau of Alcohol, Tobacco and Firearms were also assisting with the investigation.

The shooter was armed with a 9mm Glock, which was registered in her name, and "several magazines," Gahler said.

A statement from Rite Aid said the company was working with authorities and would make grief counselors available to staff.

Gov. Larry Hogan tweeted early Wednesday that he was "closely monitoring" the situation, adding: "Our prayers are with all those impacted, including our first responders. The State stands ready to offer any support."

President Trump was briefed on the shooting, "and we were monitoring," White House press secretary Sarah Sanders told NBC News Thursday afternoon.

"Three workplace active shooting attacks in just the last 24 hours should spark outrage in every American," former congressman Gabriel Giffords said in a tweet.

The incident comes one day after a heavily armed employee opened fire in the offices of a software company in Middleton, Wisconsin, injuring four people. Also Wednesday, a man opened fire in a municipal building in Pennsylvania and shot four people, including a police officer, before another officer shot and killed him.

"No matter where you work, learn, play, or live — you have a right to feel safe, and I’m horrified that that’s no longer the reality in America," Giffords added.