US school shooting: Attacker injures several people at Maryland school

A shooting took place at a high school in the eastern US state of Maryland today, officials said, reportedly leaving several people injured just days before a nationwide student-organised march against school violence.

Three people were shot in the incident at Great Mills High School, located about a 90-minute drive southeast of the US capital Washington, according to a county official quoted by The Baltimore Sun.

St Mary's County Public Schools said on its website that the school was on lockdown and the incident had been "contained" but provided no further details.

Law enforcement was on the scene.

"It happened really quickly, right after school started" after 8:00 am (local time), Jonathan Freese, a student at the school, told CNN.

"The police came and responded really quickly," Freese said. "They had a lot of officers respond."

"Right now, the police are going through classrooms," he said. "Soon we are going to be escorted from the school."

The Great Mills incident comes about five weeks after a shooting at a Florida high school left 14 students and three adult staff members dead.

Students at Marjory Stoneman Douglas High School launched a grassroots campaign for gun control following the shooting.

They have organised an event on Saturday called "March For Our Lives," which is expected to turn out large crowds in US cities, with the main event in Washington.

Emma Gonzalez, a Stoneman Douglas student, tweeted her support today for her peers at Great Mills.

"We are Here for you, students of Great Mills," Gonzalez said. "Together we can stop this from ever happening again."

Under the banner #ENOUGH, tens of thousands of US high school students walked out of classrooms around the country on March 14 to protest gun violence.

Maryland Governor Larry Hogan pledged to provide assistance.

"Our prayers are with students, school personnel and first responders," Hogan said in a tweet.