At least 14 children were killed Friday in a shooting at a Connecticut elementary school that left a total of 27 people dead, officials told CBS News senior correspondent John Miller.

Miller said that the death toll was preliminary and likely to change.

It is unclear if there was more than one gunman at the school.

Law enforcement sources told Miller that preliminary and unconfirmed information indicates that the shooter was the father of a student.

The shooter was killed and apparently had two guns, a person with knowledge of the shooting told The Associated Press. The person spoke on condition of anonymity because the investigation was still under way.

White House spokesman Jay Carney said President Obama was informed of the shooting at 10:30 a.m. ET. by homeland security adviser John Brennan.

CBS Hartford affiliate WFSB-TV reports around 600 students attend the school.

Connecticut State Police spokesman Lt. Paul Vance described the situation to CBS New York station WCBS-AM as a "very serious school shooting."

A dispatcher at the Newtown Volunteer Ambulance Corps said a teacher had been shot in the foot and taken to Danbury Hospital.

Stephen Delgiadice said his 8-year-old daughter heard two big bangs and teachers told her to get in a corner. His daughter was fine.

"It's alarming, especially in Newtown, Connecticut, which we always thought was the safest place in America," he said.

Lisa Bailey, a Newtown resident with three children in Newtown schools, told CBSNewYork.com, "Newtown is a quiet town. I'd never expect this to happen here. It's so scary. Your kids are not safe anywhere."

The superintendent's office said the district had locked down schools in Newtown, about 60 miles northeast of New York City. Schools in neighboring towns also were locked down as a precaution.

State police said Newtown police called them around 9:40 a.m.

A photo posted by The Newtown Bee newspaper showed a group of young students — some crying, others looking visibly frightened — being escorted by adults through a parking lot in a line, hands on each other's shoulders.

Students were taken to a nearby firehouse to be reunited with their parents, CBSNewYork.com reports.