The incident took place in a Houston suburb of Cypress, between 11.00 p.m. and midnight, when over 100 people, mostly young adults, were celebrating a birthday at a house, reported Xinhua citing the Harris County Sheriff's Office in a statement.
According to ABC news, upon arriving law enforcement officials described a chaotic scene rife with teenagers trying to escape the suburban residence, Harris County Sheriff Adrian Garcia said.
Over 100 people were inside the small, two-storey home when one suspect fired his gun "in apparent celebration".
"Let me describe the event last night as a birthday party gone wild," he said.
"[It was] just one of those inexplicable, crazy things when someone decides to pull a pistol and discharge it in the air, and someone else who thinks it's important to carry a pistol to a birthday party decides to pull theirs," Garcia said.
Two Cypress Springs High School students died -- one at the scene and another at a hospital, the official added.