The district has initiated a lockdown at the high school.
Galveston County Sheriff Henry Trouchesset said authorities are still trying to determine if there is more than one shooter.
Police and other local emergency responders were dispatched to the scene.
CNNSanta Fe school shooting Police cordon the school campus
A shooting was reported at a high school near Houston on Friday morning, with local media reporting that a gunman entered Santa Fe High School and began firing.
Law enforcement officers are responding to an active shooter incident at a high school southeast of Houston, Texas.
More information provided as it becomes available. Douglas Hudson told the Associated Press units are responding to reports of shots fired but could not give further details.More news: What Is 'Google One' And Do You Need To Care?
One student told KTRK his friend pulled the school fire alarm after spotting a suspect with a gun. This is an unconfirmed report.
The eyewitness said students fled the school in a panic.
Sky2 video also showed at least two Life Flight helicopters at the school.More news: Cash-stuffed designer bags seized raids on Malaysia's ex-PM
According to a law enforcement official, the Federal Bureau of Investigation is responding to offer assistance, CBS News senior investigative producer Pat Milton reports.
Santa Fe PD and Galveston County Sheriff's department are both on the scene.
"I didn't see anybody shooting, but like (the gunshots) were kind of spaced", she said, adding she heard about four shots. Santa Fe police swept the campus but found no threat.More news: Some infectious bacteria resistant to chlorine, CDC warns