DIXON, Ill. — The police chief in this northwestern Illinois city says a school resource officer saved lives when he confronted an armed 19-year-old former student at the high school.

Police Chief Steven Howell said at a news conference that the officer shot and wounded the lone gunman at Dixon High School about 8 a.m. Wednesday. No one else was hurt.

Howell says the former student fired several shots near the school gymnasium and ran away when the officer confronted him. He says the teenager turned and shot at the officer, who then returned fire.

Howell praised the officer for saving lives. He says the gunman is in custody with non-life-threatening injuries. Authorities haven’t provided the gunman’s name.

City manager Danny Langloss told Sauk Valley Media that students had been gathered in the gym for graduation practice when the shooting happened.

All schools in the city, in Lee County and about 80 miles west of Chicago, have been placed on lockdown while the shooting is investigated.

Police cars outside Dixon (Ill.) High School on Wednesday, where officials say a police officer shot and wounded a former student who had fired at him. He is in custody with what have been described as non-life-threatening injuries. | Rachel Rogers/Sauk Valley Media,distributed by the Associated Press