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GREAT MILLS (CBSMiami) – Two students were wounded, one of them critically, when a student brought a gun to school and opened fire.

Shots rang out just before classes began Tuesday morning at great mills high school, in maryland.

When it was all over, a 16-year-old girl and a 14-year-old-boy were wounded and the shooter, was dead.

“I walked into the school and I heard three gunshots and after, that’s when everybody was running outside and they were texting ‘what happened what happened?’” said sophomore Tejon Butler.

A school resource officer is credited with potentially saving lives when he confronted the shooter.

“When the SRO fired, the suspect, as described to me, fired almost simultaneously,” said St. Mary’s County Sheriff Tim Cameron.

It’s unclear if the shooter, identified as 17-year-old Austin Rollins, took his own life.

Detectives are investigating whether the armed teenager targeted his female victim.

“There was a relationship prior to this event, and to the extent that shaped this event? That’s what we’re gonna have to determine,” said Cameron.

Investigators say the shooter used a glock semi-automatic handgun.

The ATF has put an emergency trace on the weapon.

1400 students were evacuated from Great Mills and bused to another school where they are being reunited with their parents.

Great Mills High School will be closed Wednesday.

Officials aren’t sure when it will reopen.

The female victim is in intensive care with life-threatening injuries.

The officer was not injured.

This latest shooting happened as many students are calling for action against gun violence in schools, leading up to Saturday’s March For Our Lives rally in the nation’s capital.

Protests have been spreading around the nation since a teenager with an assault rifle killed 17 people at Parkland’s Marjory Stoneman Douglas High School on Valentine’s Day.