The incident occurred at the Sandy Hook Elementary School in Newtown city of Connecticut state.
Newtown resident Bindu Balasubramanian described the state of shock.
"My mind is shut down. I don't know what to say. Never experienced such a thing," she said.
A resident of Newtown for the last four years, Balasubramanian works at TUV, a certification company, which is just one mile away from the school. Her residence is about four miles away from the school.
She said she left for the office a little late on Thursday. She was approaching her office at 10 am, when she saw people gathering and the police cordoning off the area. The shooting had occurred around 9:40 am. The office was shut down and the staff was asked to leave.
One of the staffer's wife is a teacher at school but was not hurt in the attack, she said.
The gunman Adam Lanza's mother also taught at the school. He lived in New Jersey.
Connecticut Assemblyman Dr Prasad Srinivasan said he 'is shocked and saddened by the tragedy that has occurred in Newtown. My thoughts and prayers are with the residents, families, and the community."
Though the police held a press conference earlier, they provided few details. Governor Dannel Malloy, who arrived in Newtown soon after the tragedy, has scheduled a press conference later on Friday.
Photograph: A couple embrace near Sandy Hook Elementary School, where a gunman opened fire on school children and staff in Newtown, Connecticut
Credit: Adrees Latif/Reuters
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