DEVELOPING: Authorities say at least 26 people, including 18 children, were killed Friday when a gunman clad in black military gear opened fire inside a Connecticut elementary school.A law enforcement official said the shooter, who is dead, was from New Jersey and had ties to Sandy Hook Elementary School in Newtown. Authorities recovered a Glock and Sig Sauer 9mm handgun, but it was unclear who killed the shooter, who wore black combat garb and a military vest.Local news outlets report that the shooting occurred inside a kindergarten classroom, and that all the pupils in that classroom are unaccounted for. 
An official with knowledge of the situation said the 20-year-old gunman, whose name has not been released, also had a .223-caliber rifle. The motive is not yet known.Police are also questioning another man in connection with the shooting. Witnesses told the Connecticut Post that a handcuffed man, dressed in camouflage, was led out of a nearby woods by officers. Shortly after 9:40 a.m., authorities reported that a shooter was in the main office of the school. A person in one room had "numerous gunshot wounds," police told the Hartford Courant.A dispatcher at the Newtown Volunteer Ambulance Corps said a teacher was shot in the foot and taken to Danbury Hospital. Local news outlets also reported that the principal was among those shot. Parent Lisa Procaccini told Fox News that her daughter was sitting in a classroom when she and others heard gun shots. 
"She was in a small class -- a reading group and they started hearing bangs," Procaccini said. "Her teacher, and I’m grateful  for this, rushed kids into the bathroom and locked the door. They told kids it was hammering and tried to keep them calm.”"Children were crying," Procaccini said. "She did tell me about a little boy that was in a police officer’s arms, bleeding. I don’t know if she gets it."The Bureau of Alcohol, Tobacco, Firearms and Explosives said two firearms were recovered from the scene.  President Obama was notified of the shooting around 10:30 am ET, White House officials said. 
The Newtown School District has locked down schools as a preventive measure to ensure the safety of students and staff.A statement on the district's website stated that afternoon kindergarten classes have been canceled.The elementary school has close to 700 students. 
Newtown is in Fairfield County, about 45 miles southwest of Hartford and 60 miles northeast of New York City.  Click for more from CTNow.com
FoxNews.com's Cristina Corbin, Mike Levine, Jana Winter and The Associated Press contributed to this report.