At least three people, including the suspect, have died and seven others are injured after a shooting at a high school in St Louis, Missouri.

The gunman entered Central Visual & Performing Arts High School shortly after 09:00 local time on Monday.

The doors of the school building were locked and it was not immediately clear how the suspect entered.

Witnesses say lives were saved after the gunman's weapon jammed mid-attack.

The suspect, identified by police as a 19-year-old former student, exchanged gunfire with police and later succumbed to his injuries.

Data from the Education Week outlet show there have been at least 35 school shootings, in which at least one person was killed or injured, so far this year.

Earlier on Monday, a teenager in Michigan pleaded guilty to 24 charges, including terrorism and first-degree murder, after a rampage at his high school last November.