Police are on the scene of a shooting at a Maryland business park north of Baltimore.
Police are now looking for a 37-year-old suspect, Radeed Labeeb Prince.
Harford County Sheriff Jeffrey Gahler said Wednesday that Prince is associated with Advanced Granite Solutions, a company located in the Edgewood park.
The wounded were in critical condition, according to a spokeswoman for the University of Maryland Medical Center's R Adams Cowley Shock Trauma Center in Baltimore. State police said they consider him "armed and risky".
If you see the suspect, police ask you to call 911.
"He came back to our business justifying what he did was right because the other guy was saying some things that he did not like", the employee claimed in the filing, adding that Prince returned to the office three times after he was sacked.
A park and much of the surrounding area around the business park were on lockdown amid the search for Prince.
The names of the victims have not yet been released. Prince has been an employee for four months, working as a machine operator, owner Barak Caba told the AP in a brief telephone interview.
He is thought to have sped away from the scene in a 2000 black Acadia, with a DE licence plate.
A co-worker sought a peace order against Radee Prince in February, saying Prince had punched an employee in the face and returned and threatened employees.
The gunman is still thought to be on the loose, Harford County sheriff's office said.
Schools in the Edgewood, Maryland, area, are on a "modified lockdown", according to Harford County Public Schools.