CHEVERLY, Md. — Police and the public were seeking answers Monday after a gunman opened fire outside a police station in a Maryland suburb of the nation’s capital, killing an officer in what the police chief called an “unprovoked attack.”

The shooter opened fire on the first officer he saw outside the station around 4:30 p.m. Sunday in Landover, a suburb about 10 miles northeast of downtown Washington, D.C., according to Prince George’s County police chief Hank Stawinski.

A gun battle followed, with several officers shooting at the suspect, who was wounded, Stawinski said at a news conference. On Sunday night, hours after the shooting, Stawinski had few answers for reporters about what led to the gunfire.

“It wasn’t about anything,” he said of the shooting, which claimed the life of a four-year veteran of the department who would have turned 29 this week.

Police were going about their business on the quiet, rainy Sunday afternoon when the gunman fired at the first officer he saw outside a Maryland police station, prompting a gunbattle that left undercover narcotics officer Jacai Colson fatally wounded, according to officials.

Colson was pronounced dead at a hospital and the suspect was wounded but expected to survive, authorities said.

Once the first shot was fired, several officers fired back at the suspect, Stawinski said. He didn’t say how many shots were exchanged.

“Those officers did not shrink. They bravely advanced and engaged this individual,” the chief said.

Prince George’s County State’s Attorney Angela Alsobrooks called the shooting an “act of cowardice” and a “horrific act of evil.”