Another dark day in the United States.

Connecticut State Police say they are assisting local police in Newtown in response to reports of a shooting at an elementary school.

The school superintendent's office says the district has locked down schools to ensure the safety of students and staff. 

One police officer present at the scene has been cited in various US media outlets as saying one person had "numerous gunshot wounds."

Students being led from the school by State Police 

Further reports have suggested a number of injured parties, but the nature of their injuries is not yet clear.

According to CNN one shooter is dead, and police have recovered two weapons from him.

There are further, unconfirmed reports of a second shooter.

NBC Connecticut has reported that three people were transported from the Newtown school by ambulance to Danbury Hospital.

Emergency crews have set up on site with triage facilities.

There is a news conference for 1 p.m. ET. (6 p.m. GMT).

17:03 GMT UPDATE: 

Connecticut paper Hartford Courant has confirmed that children are among the dead at the scene