A 17-year-old student killed herself at an Orlando-area high school after excusing herself from class Wednesday morning, investigators say. The student shot herself with a handgun just before 8 a.m. at Lake Mary High School, Seminole County Sheriff Dennis Lemma said at a news conference.

Lemma said the 11th grade student was in class around 7:50 a.m., just before the end of first period, and asked her teacher to go to the bathroom. She went to an isolated area in the school's auditorium, and a gunshot was heard in the building about five to 10 minutes later, Lemma said.

The scene at Lake Mary High School, where a student fatally shot herself March 13, 2019 WKMG

Two school resource officers and a school nurse responded within a minute and attempted to revive the girl, but were unsuccessful, Lemma said.

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Lemma said he doesn't believe any students witnessed the shooting.

"It appears that she went out of her way to do it in an area where nobody else was at," Lemma said.

The school was placed on lockdown, and Lemma said he notified the school community via the PA system. He said the school is safe and there was no active threat. Parents were also notified via an automated voicemail, reports CBS affiliate WKMG.

Lemma said the girl's family has been notified. Her identity isn't yet being released.

"Every person's stomach is in knots right now thinking about this tragedy," Lemma said.

Lemma said his office is continuing to investigate who the gun belonged to and how the girl obtained it. He said grief counselors were being made available at the school, and encouraged anyone struggling with depression or mental health issues to ask for help.

"Let's do what we can to make sure we're talking about this," Lemma said. "Lets not turn a blind eye to it, and prevent situations like this from ever happening again."