St. Mary’s Couty Sheriff spokeswoman Cpl. Julie Yingling says there have been injuries, but she didn’t know how many or the severity. She said she had “no information” about potential fatalities.

The Baltimore Sun reported that a student said the shooting happened around 8 a.m. Terrence Rhames, 18, told the Sun that he heard a gunshot and saw a girl fall as he ran for an exit. “I just thank god I’m safe,” Rhames said. “I just want to know who did it and who got injured.”

The county sheriff said deputies are on the scene, and told parents or guardians to stay away, urging them to go instead to Leonardtown High School to reunite with Great Mills students there. The Bureau of Alcohol, Tobacco, Firearms and Explosives tweeted that its agents are going to the scene.

Maryland Gov. Larry Hogan and Rep. Steny Hoyer tweeted that they’re monitoring reports and urged people to follow the instructions of local law enforcement at the scene.