A D.C. police detective accidentally shot an Arlington man he was placing under arrest early yesterday morning in Northwest Washington after a shouting match between two motorists, police said.

Police said Detective Charles J. Jones, 43, wounded Michael G. Burns, 26, of 2301 South Jefferson Davis Hwy. while arresting him on disorderly conduct charges at New Hampshire Avenue and L Street NW. Burns, who was shot in the lower back, was taken to George Washington University Hospital, where he is listed in serious but stable condition, a hospital spokeswoman said.

Police said Jones drew his service revolver when a group of people came toward him as he tried to arrest Burns. When the group stopped moving toward him, Jones started to reholster his gun and the gun discharged accidentally, police said.

Two persons who said they witnessed the shooting told a reporter that no one in the group of about six people moved toward Jones. They said they noticed a gun in Jones' hand and then heard a shot. Kevin Nahigian, a medical student from Georgetown University, said Jones was then heard to say, "Oh, my God, I {messed} up. I didn't mean for it to happen this way."

Police said the incident is under investigation.