Up to 10 people have been killed in a school shooting in Texas.
The massacre began not long after classes began at Santa Fe High School at 7:30am Friday (local time), according to US reports.
"We were all standing (outside), but not even five minutes later, we started hearing gunshots," 14-year-old Angelica Martinez told CNN. "And then everybody starts running, but like the teachers are telling us to stay put, but we're all just running away."
"I was in the history hallway, and as soon as we heard the alarms, everybody just started leaving following the same procedure as ... [a] practice fire drill," student Dakota Shrader told KPRC.
"And next thing you know, we just hear... three gunshots, loud explosions, and all the teachers are telling us to run."
The suspected shooter was named as Dimitrios Pagourtzis, 17.
Explosive devices have been found, including pressure cookers and pipe bombs.
Officials say the gunman had a shotgun and a revolver - both owned by his father.
CNN reports it's the third US school shooting in the past eight days, and the 22nd this year. The Washington Post reports more students have been shot dead at school this year than fighting in the US Army.
US President Donald Trump said school shootings had been "going on too long".
"We grieve for the terrible loss of life and send our support to everyone affected by this absolutely horrific attack."
Mr Trump's proposed solution is arming teachers with guns.