US school shooting: Gunman dies after being shot in Maryland

A gunman who shot and injured two teenage students at a high school in the US state of Maryland was shot dead by an officer, police say.

Austin Wyatt Rollins, 17, shot a 16-year-old girl, who is in a critical condition, and a 14-year-old boy.

The attack happened on Tuesday morning before lessons at Great Mills High School in St Mary's County, 65 miles (104km) south-east of Washington DC.

Rollins had a prior relationship with the girl, Sheriff Tim Cameron said.

The school shooting comes a month after a high school shooter killed 17 in Parkland, Florida.

Blaine Gaskill, an armed campus guard, exchanged gunfire with the attacker but it is unclear if the gunman was hit by the guard's gunfire or shot himself.

• Florida survivors: Don't arm teachers

• US students in mass walkout for gun reform

Mr Cameron said the shooting began in a hallway at the school.

The gunman fired at a female and then a male student, hitting them both, he said.

"Our school resource officer who was stationed inside the school was alerted," he told reporters.

"He pursued the shooter, engaged the shooter. During that engagement he fired a round at the shooter.

"Simultaneously, the shooter fired a round as well," he said.

Mr Gaskill was not hurt, Mr Cameron said, adding that the gunman's cause of death was still under investigation.

The female student is in a critical condition in hospital.