Multiple people are dead after a shooting Friday at Sante Fe High School in Texas, sources told CNN. It was the 22nd school shooting this year.

A suspect “has been arrested and secured,” the school’s assistant principal, Cris Richardson, told the Associated Press.

The Harris County sheriff’s office tweeted that officers are on the scene and the situation is contained.

“This is no longer an active shooting situation and the injured are being treated,” according to the office.

Harris County Sheriff Ed Gonzalez said that a second person was detained and a police officer was injured.

Students were described as running when they heard gunshots ring out before 8 a.m. local time at the school. A witness told a CNN affiliate that a gunman walked into an art class and began firing a shotgun.

“We were all standing (outside), but not even five minutes later, we started hearing gunshots,” student Angelica Martinez, 14, told CNN. “And then everybody starts running, but like the teachers are telling us to stay put, but we’re all just running away.”

The school district is on lockdown, officials told CNN.

Santa Fe is 30 miles southeast of Houston and has a population of about 13,000, per CNN.