The shooting, at Sandy Hook Elementary School, comes less than a week after a deadly rampage at an Oregon shopping mall.
Police reported a gunman in the main office of the school at 9:40 am, according to a news story.
One person thought to be a shooter is said to be dead, while reports of a second shooter were unconfirmed.
“I can’t believe — in a small town like this — we’ve never had anything like this happen,” one third-grader’s father told local TV station WTNH. “I was pretty shaken up. I did not know who or what happened.”
The school was still being searched at press time.
Newtown is located about 45 miles southwest of Hartford, Conn., and 80 miles northeast of New York City. Sandy Hook Elementary teaches children from kindergarten through fourth grade.
“It was horrendous,” parent Brenda Lebinski, who rushed to the school where her daughter is in the third grade, told Reuters. “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.”
No official statement yet from President Obama, but former California Lt. Gov. Gavin Newsom posted on his Facebook page: “The second mass shooting this week, first Oregon and now Conn. We need to change our gun policies.”