The shooter, identified as 37-year-old Radee Labeeb Prince, is believed to be on the loose, according to the Harford County sheriff's office.
"Currently we have lost three" and the other two hit were seriously wounded, at the Emmorton Business Park in Edgewood, roughly 30 miles northeast of Baltimore, Harford County, Gahler told reporters. William Davis said. Two victims are in critical condition.
The suspect and the victims were all associated with Advanced Granite Solutions at the Emmorton Business Park in Edgewood. He should be considered armed and risky.
If you see Prince, you're urged to stay away from him and call 911.
He did not explain Prince's exact association with the business.
He said authorities in helicopters and on the ground were searching for Prince, who may be driving a black 2008 GMC Acadia with the DE licence plate PC64273.
"The individual out there on the loose who committed one of the most heinous crimes in the county, consider him armed and risky", a police officer said, adding "We do not think that there is an immediate threat to the community".
Multiple businesses in the area were reportedly on lockdown.
Prince has been an employee for four months, working as a machine operator, owner Barak Caba said.
The names of the victims have not yet been released.
The suspect was allegedly fired from a job earlier this year for attacking another employee.
A former co-worker sought a restraining order against him in February, the paper reports.
He said one time, Prince came to see him, and cursed and yelled at him.
A number of Harford County Public Schools in the area are on a "modified lockdown".