Students and families were reunited in emotional scenes after the shooting at Arapahoe high school in Colorado.
A 15-year-old girl was in critical condition after the shooting, suspected to have been carried out by an 18-year-old, Karl Pierson, who police say apparently shot himself at the scene.
More top news
An 'unarmed' black man, who was reported to be mentally ill, has been shot dead by police in California after his sister called for help.
"Rubble fell in on intensive care patients" in the early hours of Wednesday, medics said.
The inquiry's most senior lawyer is said to be considering stepping down after disagreeing with its chairwoman Alexis Jay over its future.