A shooting unfolded Monday afternoon at the Covenant School, a Christian elementary school in Nashville, Tennessee. At least three children and three staff members were shot and killed, officials say.

The suspect was female and allegedly in her teens was also shot and killed by authorities in the lobby area on the second floor of the school, according to police.

The suspect entered the school through a side entrance and was armed with at least two assault-type rifles and a handgun, and has not yet been formally identified. No one who was shot survived.

Nashville Metro police said the shooting began at 10:13 a.m. as the shooter made her way from the first floor to the second floor, firing multiple shots. Police reported that two officers engaged the shooter before firing and killing her at 10:27 a.m. It’s still unclear if the shooter had a connection to the school or any of the students.

All three students were rushed to Monroe Carell Jr. Children’s Hospital at Vanderbilt with gunshot wounds. A spokesperson for the hospital has confirmed all three died from their injuries.

Hospital officials also said three adult staff members were taken to Vanderbilt University Medical Center and have also died from their injuries.

According to WKRN News, Dr. Adrienne Battle, Director of Metro Nashville Public Schools, issued the following statement on the school shooting:

“As a parent, as an educator, as a human being, I’m grieving today over the tragic murder of children and school staff right here in our community. My heart goes out to the entire Covenant School community and the parents grieving the unimaginable loss of life today.

“We have been in close contact with the MNPD throughout the day, and we are providing whatever support we can to assist in their response. This is a traumatic event for the entire community, and our student support services team will be working to help our students and staff process this situation in the days to come.

“We don’t know all of the details of how or why this happened, and we may never fully know. At Metro Schools, we have invested considerable resources to strengthen security at our facilities in response to the far too many, far too often instances of school shootings across the nation over the years. We will continue to reinforce our safety protocols and monitor and follow best practices on keeping students safe from harm.”