At least three people were killed in a shooting at a St. Louis, Missouri high school on Monday, including the shooter, a former student who graduated last year, a woman and a teenage girl, authorities said.

St. Louis Public Schools announced earlier Monday that eight people, including at least two students, had been transported to a local hospital, following gunfire at Central Visual and Performing Arts high school. 

The shooter was identified Monday evening as Orlando Harris, 19, who graduated from the school last year. He has no prior criminal history and investigators were trying to determine a motive for the shooting. 

Hours after shots rang out, St. Louis Police Chief Michael Sack said the doors to the school were locked, something that "bought time" for school security officers to react.

"The security staff did an outstanding job identifying the suspect’s efforts to enter and immediately notified other staff and ensured that we were contacted," he said.

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The two victims who were killed were only identified as a 61-year-old woman and a 16-year-old girl. The deceased woman was identified as Jean Kuczka, a physical education teacher, who was taken to a hospital where she was pronounced dead Fox 2 Now reported. The teen girl was killed at the scene. 

The others injured suffered a variety of shrapnel and gunshot wounds and are being treated at local hospitals.

Officers received a call around 9:10 a.m. about an active shooter. Within minutes, authorities arrived and entered the school as students were fleeing the building, Sack said. Some of the students told the officers there was a shooter with a "long gun," he said. 

"Upon hearing gunfire, they ran to that gunfire, located the shooter and engaged that shooter in an exchange of gunfire," the chief told reporters. 

The suspected shooter was struck and was pronounced dead at a hospital, he said. No officers were injured during the confrontation. 

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Images from outside the school showed buses lined up and students crowded in the parking lot. Police soon established a "reunification location" at Gateway Stem High School, allowing parents to pick up their children.

Rep. Cori Bush, D-Mo., lamented on the rash of school shootings that have become all too common. 

"Today is one of those days that we pray never happens across this country," she said at the scene. "Parents wake up everyday in this community praying that it's not their school, that it's not their child."
 

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."

Sack said he wasn't aware of school security guards were armed.

"It may not be a bad idea to have the security officers armed at those schools," said before confirming authorities were searching Harris' home. 

He noted the Missouri gun laws were "very broad" and that guns are too easily accessible in St. Louis. 

Agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives Kansas City, Missouri field office were on the scene and the FBI was assisting local law enforcement. 

Sen. Josh Hawley, R-MO, praised the "swift response of local law enforcement" in a statement to Fox News.

"Devastating news in St. Louis," he wrote. "My office is in contact with local authorities, and we stand ready to offer all assistance possible."

Missouri Gov. Mike Parson reacted to the shooting on Twitter, saying: "Our hearts go out to the victims and their families of this morning’s shooting at Central Visual and Performing Arts High School in St. Louis. Our office has been briefed on this tragedy."

The Associated Press contributed to this report.