A Bladensburg police officer who died after a collision in Anne Arundel County had shot himself while driving, the Maryland medical examiner determined.

Officer Brian Johnson died from a gunshot wound to the upper body, and his death was a suicide, Anne Arundel County police officials said Monday, citing findings by the medical examiner's office in Baltimore.

The incident occurred about 9 a.m. Saturday on Route 100 near Catherine Avenue in Pasadena. Johnson shot himself while he was alone in his marked police vehicle, and his cruiser crossed the median and collided into a vehicle that was traveling in the opposite direction, police said.

When police found Johnson at the scene, they saw that he had "significant injuries," officials said. Johnson was taken to a hospital, where he was pronounced dead.

Anne Arundel County police spokesman Justin Mulcahy said that "it's unusual" for someone to commit suicide while in a moving vehicle.

The driver of the vehicle that Johnson crashed into was treated at the scene and released. While police were investigating the incident, part of westbound Route 100 was completely closed for a few hours, and traffic on eastbound Route 100 was reduced to one lane.

Johnson was off-duty at the time of the incident. Bladensburg police Lt. Scott Davis said that Johnson was employed by the town for about 10 years, working as a police officer for about 7 of those years.

"He was definitely an asset to the agency," Davis said.

In addition to working as a police officer, Johnson was also a volunteer firefighter in Bladensburg. He is survived by his wife, three children and other family members.

"It is with the deepest of regrets, through heavy hearts and many tears our family has lost a great fireman and Bladensburg Police Dept. has lost a great Police Officer/Detective," the Bladensburg Volunteer Fire Department said in a statement. "We shall forever remember the great times and the many things that you have taught to so many of our firefighters over the years."