A Maryland high school was on lockdown following a shooting on Tuesday morning, the local school district said in a statement, but the incident has since been "contained."

The shooting took place at Great Mills High School in St. Mary's County, and it was not clear whether there were injuries.

It occurred amid a re-energized national debate over school shootings in the United States following an attack on Feb 14 at Marjory Stoneman Douglas High School in Parkland, Florida, where a gunman killed 17 students and faculty.

The St. Mary's County sheriff's office confirmed an incident at the school and urged parents in a Twitter post not to approach the school. Federal investigators from the Bureau of Alcohol, Tobacco, Firearms and Explosives were heading to the school, the agency said.

Great Mills is a town about 70 miles (110 km) south of Washington.

Reuters