Dr. Cris Richardson, assistant principal of Santa Fe High School tells reporters that there was an active shooting at the school, and "that person has been arrested."
Richardson could not comment on injuries.
At least three helicopters have landed in the school's parking lot, video from CNN affiliate KTRK just shows. Officials were just seen wheeling a stretcher toward one of them. It isn't clear if an injured person is on the stretcher.
Patients from Santa Fe High School are currently en route to University of Texas Medical Branch in Galveston, according to Raul Reyes Director of Media Relations for University of Texas Medical Branch.
The total number of patients is unknown at this time.
A Santa Fe High School student described the moment they all heard gunshots.
"So, it was just a normal-like class day. We all were doing our work in first period. And then all of a sudden like it's a fire drill," 14-year-old junior Angelica Martinez said.
That's when everybody starts running, she said, despite teachers telling them to "stay put."
"But we're all just running away."
Myles Kanipes, son of Sante Fe High School athletic director and football team head coach Mark Kanipes, confirms to CNN that his dad is on lockdown on campus, outside of the building, but is safe.
Kanipes told CNN that his dad is currently escorting kids across the street to the Shell station to get them safe.
Kanipes told CNN that other football coaches at the school were already inside the building when the shooting began, and he is waiting to hear from them.
A group of students were just directed by police to a nearby field and told to empty their backpacks, video from CNN affiliate KTRK shows.
Kim Sullivan is the parent of a 17-year-old senior at Santa Fe High School. She says her daughter called her and said there was a shooting at school.
Her daughter said they were told to run, so they ran to the Shell gas station across the street from the school.
Sullivan says there are a lot of kids and confused parents trying to find their kids.
According to an eyewitness account given to a CNN affiliate, a gunman at a high school in Santa Fe, Texas, entered a classroom and began shooting with what appeared to be a shotgun.
The witness says they saw a girl shot in the leg.
The agency just announced on Twitter:
Santa Fe High School is located about 40 miles south of Houston in Santa Fe, a city in Galveston County of about 12,000 people.