At least three people were killed after a gunman opened fire Thursday at a manufacturing facility in the US state of Maryland, according to the Washington County Sheriff's Office.

Deputies responded to the shooting at Columbia Machine Inc. in the town of Smithsburg at approximately 2.30 p.m. Eastern Time (1830GMT), said the office in a statement.

"Units immediately responded and located 4 victims, 3 of which were deceased at the scene and one who was critically injured," it said.

It said the suspect fled the scene prior to law enforcement's arrival.

"The description (of the suspect) was quickly released to additional responding units and the suspect’s vehicle was encountered by Maryland State Police in the area of Maplesville Road and Mount Aetna Road, (and) gunshots were exchanged between the suspect and the trooper. Both were injured and transported for medical treatment," the statement added.

The shooting came in the wake of a series of mass shootings that have shocked and angered Americans and the country’s leadership./aa