One student was shot this morning, the first day of school, at Perry Hall High School, Baltimore County Police say.
The student has been taken to an area hospital, authorities said. Details were not available on the student's condition. Police have taken a suspect into custody.
Students are being escorted to the Perry Hall Shopping Center at the corner of Ebenezer Road and Belair Road, where parents can meet them, police said.
Baltimore County Councilman David Marks lives next door to the school and said he's been hearing "a lot of helicopters."
He said he's received dozens of phone calls this morning from worried parents and residents.
"It's horrifying," said Marks, who graduated from the school. "This is a very peaceful community, and my prayers are with anyone who's been impacted by this."
U.S. Education Secretary Arne Duncan was at the school last Wednesday to address 800 Baltimore County English teachers to boost morale.
Baltimore Sun reporters are going to the scene now. Check back for details.