Emily Palmeter was found lying on the floor of the apartment police said, in the 5100-block of Via Vallarta at about 1:30 a.m. Saturday morning.
Palmeter and a friend were visiting two men who lived in the complex, ages 18 and 19. The four had gone into a hot tub, then Palmeter and one of the men went inside, police said.
The man came out a few minutes later and said something was wrong, detectives said.
An autopsy has been scheduled. Police said there were no obvious signs of trauma and that the girl has no history of illness.
On Monday, when Palmeter's parents were contacted about their daughter's death, they called it an accidental death. When asked about specifics, they would not reveal any other details.