WATCH - Nashville shooter who killed 6 drew maps of school, used 3 deadly weapons; CCTV footage released

Three children and three adults are dead after a shooting on Monday at a private school in the US city of Nashville, according to local authorities. Police said the shooter was also killed.

The 28-year-old female shooter was armed with at least two semi-automatic rifles and a handgun and was shot by police, Don Aaron, a spokesperson for Metropolitan Nashville Police Department, said.

Besides the deceased, no one else was shot, Aaron added. 

Shooter had detailed map of school

Police received the first call about an active gunman at 10:13 a.m (15:13 UTC) local time. Officers began clearing the first floor of the school when they heard gunfire from the second floor, Aaron said.

Authorities said the suspect had drawn up a detailed map of the school, indicating possible entry points.

About 200 students from preschool through sixth grade attend the Covenant School, a Presbyterian school founded in 2001.

Aaron said that since the school is a church-run school, no police officers were present or assigned to the school at the time of the shooting.

Tragic morning for Nashville

During a media briefing, Nashville police said that the three children who were killed were all aged nine. Three adult staff members were also killed by the shooter.

Three students were pronounced dead after arriving at Monroe Carell Jr. Children's Hospital at Vanderbilt with gunshot wounds, John Howser, a hospital spokesperson, said in a statement.

"I was literally moved to tears to see this and the kids as they were being ushered out of the building," Metropolitan Nashville Police Chief John Drake said during a afternoon news conference. 

Drake said the 28-year-old suspect had previously been a student at the school. He

also gave examples of the shooter's prior planning for the targeted attack. "We have a manifesto, we have some writings that we're going over that pertain to this date, the actual incident," Drake said.

"In a tragic morning, Nashville joined the dreaded, long list of communities to experience a school shooting," Nashville Mayor John Cooper wrote on Twitter.

Biden urges Congress to act

US President Joe Biden wants Congress to do more to stem gun violence, the White House said in response to the tragedy.

He has repeatedly called for stricter gun laws and has tightened regulations slightly in the past.

"How many more children have to be murdered, before Republicans in Congress will step up and act to pass the assault weapons ban," Press Secretary Karine Jean-Pierre asked.

The president said the shooting is a "family's worst nightmare."

There have been 89 school shootings in the US so far in 2023, according to the K-12 School Shooting Database.

They classify a school shooting as anytime a gun is discharged on school property.

Last year saw 303 such incidents, the highest of any year in the database, which goes back to 1970.