Children, principal among the dead in U.S. elementary school shooting

The United States is in a state of shock after a gunman killed at least 27 people including as many as 18 children inside a Connecticut elementary school on Friday.

State police have confirmed that at least one shooter opened fire at the Sandy Hook Elementary School in Newtown, Connecticut. The school hosts about 600 students between the ages of five and 10 years of age.

The Associated Press reports that at least 18 of the victims were young children. State police confirmed the shooter was found dead in the building, and various reports suggest two guns were recovered.

Local news cited unconfirmed reports that another suspected shooter has been placed in custody.

More on the Newtown tragedy:

State officials were horrified by the tragedy. A spokesman said Gov. Dan Malloy was meeting with parents and has been in contact with President Barack Obama.

State police said officers were notified shortly after 9 a.m. Local and state police rushed immediately to the scene and began sweeping the building. The entire school was searched and students were evacuated, Lieut. Paul Vance told reporters.

Video and images showed the terror at the scene, as adults led long lines of terrified children out of the school to safety. Parents rushed to the scene to reunite with their children as police crews, including SWAT teams and K-9 units, combed the schoolyard.

"It was horrendous," said parent Brenda Lebinski, who rushed to the school where her daughter is in the third grade. "Everyone was in hysterics - parents, students. There were kids coming out of the school bloodied. I don't know if they were shot, but they were bloodied."

The school's principal and psychologist were among the dead, according to a CNN report.

The Hartford Courant has reported that much of the shooting occurred inside a kindergarten classroom. One entire class of students remains unaccounted for, the Courant reports.

Stephen Delgiudice, the parent of a student at the school, told CBS News that it appears the shooting began in the principal's office. His daughter told him that part of an argument was broadcast over the school's intercom before the shooting began.

Dave Altimari, a reporter with the Hartford Courant, reported on Twitter that state police were indicating that the attack could be the worst school shooting in U.S. history.

Earlier this year, a gunman opened fire in an Oregon shopping mall, killing two people and himself. Twelve others were shot and killed during a midnight screening of the Batman movie. Fifty-eight others were injured.

With files from Reuters