There are multiple fatalities from a shooting at Santa Fe High School near Galveston, Texas, this morning, law enforcement sources told ABC News.
Harris County Sheriff Ed Gonzalez said one person is in custody and a second person is detained. The suspect appears to be a student, a local law enforcement official said.
Law enforcement officials told ABC News authorities are also investigating to see if an explosive device was left behind in the school.
Witnesses said the shooting took place in an art class, ABC station KTRK in Houston reported. The incident has since been contained.
One student told KTRK she was in first period when the fire alarms went off. Students were told to evacuate and staff members instructed them to run across the street and hide.
"It has been happening everywhere. I wasn't surprised it happened here," one student told KTRK. "I was just scared. I just kept running."
An unknown number of people are also injured. Among the injured is a police officer in unknown condition, the sheriff said.
The University of Texas Medical Branch said it is treating three patients with gunshot wounds; two are adults and one is a child.
Agents from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives responded to the scene. Ambulances and helicopters have also swarmed the school.
President Trump tweeted, "School shooting in Texas. Early reports not looking good. God bless all!"
This story is developing. Please check back for more updates.