At least six college students were transported to the hospital following a series of overdoses at a fraternity party Saturday night, according to the Boulder Police Department.

Boulder is home to the University of Colorado campus.

In a news release Sunday morning, police said officers were called between 10 and 10:30 p.m. to the Kappa Sigma fraternity, located at 1100 Pennsylvania Ave., for a report of at least six men ill from overdosing.

Police said the students were treated on-scene, and then transported to the hospital.

As of Sunday, all six college students are in stable condition, according to authorities.

One of the college students’ prognosis was “initially grave,” the police said in a statement.

Initial investigations indicate the students consumed a “possibly tainted batch of cocaine” at the party, police said, adding alcohol was involved.

Authorities continue to investigate the cause of these overdoses.

Detectives are investigating whether the series of overdoses was the result of pledging at the fraternity.

“The Boulder Police Department would like to remind the community about the dangers of illegal drug and alcohol consumption,” police officials said.

A CU spokesperson told The Denver Gazette the Kappa Sigma fraternity is an expelled fraternity that is off-campus, separate from the on-campus Phi Kappa Sigma fraternity.

“While this news is devastating to our campus community, we are thankful that all students are expected to recover,” the CU spokesperson said.

“Kappa Sigma has not been a recognized Greek chapter at CU Boulder for nearly 20 years and was expelled from an unaffiliated interfraternity council in 2015 due to violations over time involving safety and welfare concerns,” the spokesperson said. 

The CU Boulder’s Division of Student Affairs, Counseling and Psychiatric Services and the Office of Victim Assistance are “working together to communicate with those directly impacted and provide support,” CU officials said, adding the university is working closely with Boulder police during the investigation.

CU Boulder’s Division of Student Affairs will determine any necessary disciplinary action, campus officials said.

Authorities ask anyone with information to contact the Boulder Police tip line at 303-441-1974.

The Denver Gazette has reached out to Kappa Sigma officials for further comment.