Read more on this story from CNN affiliate KOMO.
(CNN) -- Young women at a party attended by about 50 Central Washington University students and other young people were the primary target of spiked drinks, authorities said Saturday.
The incident resulted in "multiple" reports of overdoses.
Some of the victims said they had consumed only one or two beverages before becoming ill, Cle Elum-Roslyn Police Chief Scott Ferguson said.
"Their level of intoxication just didn't seem to make sense," he told CNN Radio.
Central Washington University students who attended the party told CNN affiliate KOMO on Saturday that they believe a bottle of vodka at the party had been spiked with a date-rape drug known as "roofies."
They said several people at the party used vodka from the bottle to make mixed drinks. Those who brought their own alcohol, drank beer or didn't drink any alcohol were not affected, the students told KOMO.
Ferguson would not comment on the type of drug placed in the beverages. He said he will ask the Washington State Patrol Crime Laboratory to expedite test results.
Police do not know who spiked the drinks.
"Whatever occurred up there wasn't consensual," Ferguson told CNN.
Officers initially responded to an 11:09 p.m. call Friday about a female found unconscious in a vehicle in a grocery store parking lot, Ferguson said.
Friends of the victim told authorities to go to a residence in Roslyn, according to a statement from the Cle Elum Police Department.
An officer entered one room and took a man into custody who was having sex with a semi-conscious young woman, said Ferguson.
Police later determined the woman was the girlfriend of the young man. She exhibited signs of having ingested a spiked drink, Ferguson said, and was taken to the hospital and later released. Her boyfriend was detained and questioned, but not booked. The investigation of that incident -- which authorities described earlier as a "possible sexual assault" -- continues, Ferguson said.
Several others at the party appeared to be suffering from overdoses at the residence.
None of the underage people who overdosed meant to get high or unconscious, said Ferguson, and none had more than one or two drinks, KOMO reported. Rather, he said, they appear to be victims of a scheme to render them unconscious and unable to resist or defend themselves.
The woman found in the parking lot remained in the hospital Saturday in stable condition, police said. Twelve people, 11 of them female, initially were taken to hospitals, police said. All except one were released.
The party took place at a rental home about 30 minutes from the university campus in Ellensburg, police said. The owner of the home was not at the party, police said.
Police interviewed about 35 others who attended the party, which they said was organized by a Central Washington student.
The university said it is "shaken and saddened" about the incident.
"CWU strictly enforces state law and university policy on underage drinking and illegal drug use," it said, adding that freshmen are educated on drug and alcohol abuse and sexual assault.
"Despite our best efforts, however, students sometimes make bad choices," the university said.
Students identified as being involved with the party will have a conduct hearing that could result in an intensive education course, referral to counselors or suspension, it said.
The school will hold information sessions Saturday and Sunday at residence halls, the statement said.
Police and schools typically warn young people to be careful about ingesting beverages. "Roofies," a street name for Rohypnol, is a tasteless and odorless drug, Boston University says in a fact sheet on its website, and easily dissolves in beverages.
The fact sheet advises students to watch their drinks, avoid punch bowls and not to accept opened beverages.
CNN's Barbara Hall, Nick Valencia and Jeremy Ryan contributed to this report.