The two suspects, identified as Willie Young and Randy Stewart,18, were arrested on Monday, the Harris County Sheriff's Office said in a press release. Young has been charged with deadly conduct, and Stewart with aggravated assault, Xinhua reported.
Strangers invited through social media-Twitter and Instagram.
The shooting occurred late on Saturday night when nearly 100 people, mostly young adults and teens, were celebrating a birthday at a home in the Houston suburb of Cypress.
The incident was described as a "birthday party gone wild" by Sheriff Adrian Garcia on Sunday. The massive party reportedly turned violent when a first celebratory gunfire led to random shootings into the crowd, prompting panicked people to scramble for life. Some even broke second-floor windows and jumped.
Nineteen others were injured, 18 with gunshot wounds and one with a broken leg.
Authorities also put some of the blame on social media, as the birthday party was reportedly advertised on Twitter and Instagram to invite strangers to home.
No firearms were recovered at the scene, but several bullet casings were found, the sheriff said. No drugs or alcohol is suspected in the shooting.