A teenager and an adult were killed in a school shooting in St. Louis and police won't say how the shooter entered the building

• Three people, including a gunman, were killed in a shooting at a St. Louis high school, police said.

• Police have not revealed how the shooter was able to enter the building.

• Six other people were injured and are being treated for shrapnel wounds, gunshot wounds and cardiac arrest.

A shooting at a high school in St. Louis, Missouri, left three people dead, including an adult woman, a teenage girl and the shooting suspect, local police said.

It remains unclear how the shooter got into Central Visual and Performing Arts High School in South St. Louis, and police have declined to give an answer.

“The doors were locked” St. Louis Police Department Police Chief Michael Sack told reporters Monday. “School was closed.”

Sack praised the school's security team, saying they did an “outstanding job identifying the suspect's efforts to gain entry, immediately notifying other staff members and ensuring we were contacted.” .

“The door made the suspect think. It bought us some time,” Sack said.

When asked by another reporter how the shooter got into the school if the doors were locked, Sack replied “we're not going to talk about that.”

Sack noted that the shooting took place on the third floor of the school, but it's unclear how the shooter got there.

Sack said his department received a 911 call about an active shooter at the school at 9:10 a.m. local time.

A few minutes later, police arrived on scene and entered the school as the children fled the building.

The suspect – identified as a man “about 20 years old” – was carrying a long gun, Sack said.

When police found the shooter in the school, they exchanged gunfire, eventually hitting the shooter, Sack added.

The shooter was then transported to a local hospital where he was pronounced dead. His cause of death and identity have not been released.

A total of eight people, including the shooter, were transported from the school to local hospitals, Sack said.

One of those people was an adult woman who died from gunshot wounds. She was also pronounced dead at the hospital.

The deceased teen was pronounced dead at the scene from suspected gunshot wounds.

Those still being treated at the hospital have a variety of injuries, Sack said, including shrapnel and gunshot wounds. The St. Louis Post-Dispatch reported that one person was being treated for cardiac arrest.

The St. Louis Police Department and Central Visual and Performing Arts High School did not immediately respond to Insider's requests for comment.

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