An off-duty Washington, D.C., police officer was fatally shot while sitting in a parked car in Baltimore and a woman with him was injured, authorities said Saturday.

Baltimore police said in a statement that officers found 40-year-old Tony Anthony Mason Jr. with gunshot wounds early Saturday morning. He died of his injuries at a hospital.

The Metropolitan Police Department in Washington said Mason, a sergeant, was a 17-year veteran of the force. Public information officer Sean Hickman referred all further inquiries to Baltimore police.

According to the statement from Baltimore police, investigators believe Mason and a 43-year-old woman were inside the car when an unknown suspect approached, began shooting and then fled.

The woman, who wasn't identified, suffered a gunshot wound to her leg and was taken to a hospital.

No information about a motive was immediately released, and a spokesman said Saturday afternoon that he had no new updates on the ongoing investigation.

David Simonetti, the director of the police academy at Hagerstown Community College, told the Baltimore Sun he worked with Mason from 2004 to 2009 and described him as a tough, diligent officer.

"He was just the nicest guy — always happy to see you and greeted you with a smile," Simonetti said. "He'd do anything for you, without having to be asked."

Mason's killing came amid a push by activists for a weekend cease-fire in Baltimore, which has been in the throes of a crime surge for more than two years.

The Bureau of Alcohol, Tobacco, Firearms and Explosives is offering a reward of up to $10,000 for information leading to the arrest and conviction of the person responsible.