Portland police say the officer whose gun discharged during a special reaction team raid to catch an armed fugitive Tuesday night is an experienced, well-trained member of the team and the department is still trying to determine what went wrong when he shot himself in the foot.

Sgt. John Nueslein, an evening shift supervisor who has been on the force for nine years, is seeing a specialist today about the injury to his foot.

Nueslein was one of about 15 team members approaching an apartment at 41 High St. at 8:45 when the weapon, a semi-automatic police version of the M-16, discharged.

The team, trained in special weapons and tactics, was called in because the suspect, Scot Stolkner, 34, is a convicted felon and a suspect in an earlier armed robbery and a separate case of terrorizing with a gun.

While two officers tended to Nueslein, the rest of the team entered the apartment and arrested Stolkner without incident.

Police seized a loaded .380 semi-automatic handgun, as well as ecstasy, heroin and $3,500 cash, said Capt. Ted Ross, who was overseeing the operation.

Deputy Chief Joseph Loughlin said the department will look into the circumstances of the accidental discharge but said that accidents are not unheard of during such operations in police departments across the country.

Because the weapon was properly pointed at the ground during the approach to the apartment, the round pierced Nueslein’s boot and the fleshy part of his foot and did not endanger anyone else, he said.

Officers are taught to keep their fingers off the trigger until they confront the target, he said. The incident is the first time in the team’s 22-year history an officer has been injured by gunfire, he said.

The gun has been tested at a range and while it was found to have some maintenance issues, it appears to be functioning properly, he said.