Donald A. Bowen, 45, a lieutenant with the Prince George's Fire Department who also was a deputy chief for the Calvert County Volunteer Fire Department, was killed Saturday when the ladder truck he was driving went out of control and overturned on Rte. 4 south of Broomes Island Road in Calvert County.

A Prince George's County spokesman said Mr. Bowen and another volunteer fireman with the Calvert County volunteer department, Michael L. Moore, 24, were responding from their fire station in Prince Frederick to assist victims of an automobile accident on Long Beach Road in Lusby, Md., when the accident occurred.

According to the spokesman, "road defects" contributed to the accident, which occurred at a point where a newly constructed dual lane roadway merges back into a single lane.

Both Mr. Bowen and Mr. Moore were thrown from the fire truck and, as it rolled over, Mr. Bowen was crushed, the spokesman said. Mr. Moore was transported to the Shock Trauma Center in Baltimore, where he was treated for a broken ankle, internal injuries and massive back bruises. Three person in the automobile accident to which Mr. Bowen and Mr. Moore were going were transported to Calvert Memorial Hospital.

A lifelong resident of Calvert County, Mr. Bowen joined the Calvert County Volunteer Fire Department when he was 17. He subsequently held every office with the department and for the past 20 years was a chief officer. At the time of his death, he was deputy chief and company training officer.

In 1966, Mr. Bowen joined the Prince George's County Fire Department and was assigned to the Oxon Hill Fire Station. He was promoted to sergeant in 1968 and made a lieutenant in 1974. He was a former station officer at the Bowie stations and most recently served as assistant to the deputy chief for fire suppression. He also had operated a fire extinguisher business for the past nine years.

Mr. Bowen was a past president of the Southern Maryland Volunteer Firemen's Association and the Calvert County Volunteer Firemen's Association. He was an instructor for the Maryland Fire and Rescue Institute, had served as chairman of the fire safety committee of the Pleasant Peninsula Plan and was a member of the Calvert County Fire Commission and the Brotherhood of Christian Fire Fighters.

Before joining the Prince George's fire department, Mr. Bowen, who lived in Huntingtown, Md., worked for the Chesapeake and Potomac Telephone Co. in Prince Frederick for about 15 years.

Survivors include his wife, Dorothy; a daughter, Michelle: his mother, Nellie H. Bowen, and a brother, Carl B. Bowen, all of Huntingtown, Md.

The family suggests that expressions of sympathy be in the form of contributions to the Calvert County Volunteer Fire Department in Prince Frederick County, Md.