Multiple fatalities are being reported in a shooting at a Texas high school, which is on lockdown.
One person is in custody after the attack at the Santa Fe High School, about 40 miles (65 km) south of Houston, according to school officials.
The school district has confirmed people were injured in an "active shooter" incident as classes began.
It is unclear if the attacker was a student. Police have not yet confirmed any fatalities.
News helicopters filmed students emptying their backpacks in front of armed officers in a field outside the school.
Local media are reporting the shooting began as the fire alarm went off. It is not clear how the alarm was activated.
One 10th grader told networks she had an asthma attack while hiding in the woods.