SOUTH PORTLAND —  A School Department custodian summonsed for the threatening display of a weapon and carrying a concealed weapon was already injured when he entered school administrative offices this week, according to police.

Andrzej Szpara, 53, of North Sebago, was charged with the misdemeanor offense following the incident Wednesday morning. He was also issued a criminal trespass notice that bars him from school property. Szpara was not arrested.

Szpara had a torso injury that was apparently self-inflicted when he went into the School Department’s Central Office, according to Lt. Frank Clark. Szpara withdrew a folding knife from somewhere on his person before immediately and voluntarily dropping it, Clark said.

Clark said that Szpara did not make any threats and did not display aggressive behavior. Although the charge Szpara faces includes “threatening” in its name, Clark said it was the concealed weapon element that applies in Szpara’s case.

Szpara’s injury was not considered life-threatening, Clark said. A Maine Medical Center spokeswoman said today that Szpara had been treated and released.

Superintendent Suzanne Godin said a personnel investigation is under way but that she could not comment further.

Steve Doherty, vice president of the South Portland Service Employees Association, released a statement describing Szpara as “an excellent worker and a dedicated public employee.” The statement expressed sadness over the incident and stated that the union hopes he is able to move forward in a positive manner.