Two other teens were hurt in the shooting that happened Sunday at The Henry at Liberty Hills Apartments off Liberty River Drive, near Highway 90 and the Beltway.
Authorities say between 25 and 30 teenagers were present with no parental supervision.
"I only know I heard two gun shots," apartment resident Grecia Garcia, who jumped out of her bed to call 911, said. "Really loud. I live right by the pool. Third floor. It was just so scary, a lot of people were coming out of the pool. I'm not sure what was going on. I saw a lot of kids coming out."
"When it starts in the summer, yes, they start coming from different places, and late," said Miguel Tejero, another resident. "This community doesn't have security in the night, they come inside (to party.)"
And most of the times, resident Derrick Dunlap says, the gatherings are loud, but not necessarily violent.
"I believe they love the pool over there so a lot of kids come go swimming," he said. " It's usually real nice around here, so you usually don't have to hear about anything. Real scary last night."
The sheriff's office believes everyone involved is a teenager - around 15 to 17 years old, and that there were multiple shooters who fired into the crowd.
Investigators have only been able to speak with a few people, so deputies are urging anyone with information to call the Harris County Sheriff's Office.
Galena Park ISD, which serves this area, says it is also looking into the incident to see how many of their students were involved.