About eight people have been killed on Friday in a shooting at a Texas high school, say police.
Harris County Sheriff Ed Gonzalez told reporters the majority of the dead at Santa Fe High School were students.
A student was held after the attack. Police said explosive devices were found at the school, 40 miles (65km) south of Houston, and off-campus.
The death toll makes this the deadliest school shooting since the one in February at Parkland, Florida.
That attack left 17 dead and spawned a nationwide youth-led campaign for gun control.
Santa Fe Police Chief Jeff Powell said: "There have been explosive devices found inside the high school, and in the surrounding areas adjacent to the high school."
He advised residents to be aware of any suspicious objects they find.
"Do not touch any items that look out of place," he said, warning residents to immediately call police.
He said a Santa Fe school police officer was among the injured.
Two hospitals south of Houston said they had received nine patients from the school shooting.
Clear Lake Regional Medical Center said it admitted seven, and Mainland Medical Center received two.
President Donald Trump in a tweet said the situation was not looking good.