Washington - A 17-year-old student armed with a handgun shot and critically wounded a female classmate at a Maryland high school on Tuesday, officials said, in an outburst of violence just days before a student-organised nationwide march for gun control.St. Mary's County Sheriff Tim Cameron said the assailant, identified as Austin Rollins, died of a gunshot wound after a school security officer "engaged" with him at Great Mills High School in southern Maryland.Cameron said the security officer fired a shot at Rollins, but it was not immediately clear if the officer struck the gunman or whether he had committed suicide.The Great Mills shooting comes about five weeks after a massacre at a Florida high school left 14 students and three adult staff members dead and sparked a grassroots campaign for tougher laws on gun ownership.Cameron said Rollins produced the handgun, a Glock semi-automatic, in a school hallway shortly before classes were due to begin and shot a 16-year-old girl with whom he had a "relationship"."There was a relationship prior to this event," the sheriff said. "As to how that shaped this event, we'll have to determine."A 14-year-old male student at the school was also shot and wounded during the incident, Cameron said. He was in stable condition in hospital.Cameron initially said the 14-year-old student was shot by Rollins, but he later indicated that the exact circumstances were still unclear.The sheriff said that Blaine Gaskill, the deputy sheriff responsible for school security, had responded to the gunfire in the school hallway within "less than a minute" of the shooting of the 16-year-old girl."He responded exactly as we train our personnel to respond," Cameron said."He pursued the shooter, engaged the shooter," he said. "During that engagement, he fired a round at the shooter. Simultaneously the shooter fired a round as well."In the hours to come, in the days to come, through detailed investigation, we will be able to determine if our school resource officer's round struck the shooter," he said.'I'm so tired'Following the shooting in Great Mills, located about a 90-minute drive southeast of the US capital Washington, students were evacuated to a nearby school where they were reunited with their parents, Cameron said."It happened really quickly, right after school started," Jonathan Freese, a Great Mills student, told CNN."The police came and responded really quickly," Freese said. "They had a lot of officers respond."Mollie Davis, who identified herself on Twitter as a student at Great Mills, posted a series of tweets about the shooting."Now my school is the target," she said. "WHY DO WE LET THIS KEEP HAPPENING??? I'm so tired I'm so tired.""You never think it'll be your school and then it is," Davis said. "Great Mills is a wonderful school and somewhere I am proud to go. Why us?"