A gunman who shot and injured two students at a high school in the US state of Maryland has died of a gunshot wound, police say.
The two students are being treated in hospital. One is critically ill.
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.
It comes a month after a high school shooter killed 17 in Parkland, Florida.
An armed campus guard exchanged gunfire with the attacker – who has not been identified – but it is unclear if the gunman was hit by the guard’s gunfire or shot himself.
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St Mary’s County Sheriff Tim 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,
The school security guard 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.
Some 1,600 students attend the school in the community of Great Mills near the Chesapeake Bay.
Federal agents from the FBI, and the bureau of Alcohol, Tobacco, Firearms and Explosives – as well as local police – are at the school investigating the incident.
One Twitter user, who appears to be a student at the school, posted about the shootings.
Maryland Governor Larry Hogan has also expressed concern, saying “prayers are not enough”.
“Today’s horrible events should not be an excuse to pause our conversation about school safety,” he said in a statement.
“Instead, it must serve as a call to action.”
New York Governor Andrew Cuomo said the attack serves as “another tragic and exasperating reminder of the enduring threat of gun violence”, and called upon “our so-called leaders in Washington” to take action to stem gun attacks.
The shooting comes four days before the March for Our Lives rally for student safety inspired by the 14 February massacre at Marjory Stoneman Douglas High School in southern Florida.