A gunman broke into a St. Louis high school Monday morning, fatally shooting a woman and a teenage girl and injuring six others before police killed him in an exchange of gunfire.

The shooting just after 9 a.m. at Central Visual and Performing Arts High School forced students to barricade doors and huddle in classroom corners, jump from windows and run out of the building to seek safety. One terrorized girl said she was eye-to-eye with the shooter before his gun apparently jammed and she was able to run out.

Speaking at a news conference, Police Commissioner Michael Sack said the shooter was about 20 years old but did not provide a name for him or his victims. He declined to say if the woman killed was a teacher.

Sack said security officials initially became alarmed when the man tried to get into the locked school building. He declined to say how the man eventually got inside, armed with what he described as a long gun.

St. Louis Schools Superintendent Kelvin Adams said seven security guards were in the school at the time, each at an entry point of the locked building.

Officers worked to get students out of the three-story brick building, then “ran to that gunfire, located that shooter and engaged that shooter in an exchange of gunfire,” killing him, Sack said.

Sack said some of the six people hospitalized suffered gunshot wounds, while others were struck by shrapnel. He did not provide any information on their conditions.

One student, 16-year-old Taniya Gholston, told the St. Louis Post-Dispatch she was in a room when the shooter entered.

“All I heard was two shots and he came in there with a gun,” Gholston said. “And I was trying to run and I couldn’t run. Me and him made eye contact but I made it out because his gun got jammed. But we saw blood on the floor.”

Ninth-grader Nylah Jones told the Post-Dispatch she was in math class when the shooter fired into the room from the hallway. The shooter was unable to get into the room and banged on the door as students piled into a corner, she said.

“Our children shouldn’t have to experience this,” a shaken St. Louis Mayor Tishaura Jones said at the news conference. “They shouldn’t have to go through active shooter drills in case something happens. And unfortunately that happened today.”

Sack said the shooting happened at 9:10 a.m. Crime tape was placed around the school and some parents arrived to pick up kids and check on their safety. The school district, in a tweet, said students could be picked up at another school building or a nearby grocery store.

Central Visual and Performing Arts High School is a magnet school specializing in visual art, musical art and performing art with about 400 students. The district website says the school’s “educational program is designed to create a nurturing environment where students receive a quality academic and artistic education that prepares them to compete successfully at the post-secondary level or perform competently in the world of work.”