Boulder police said Tuesday that five college students from the Kappa Sigma fraternity became seriously ill over the weekend after drinking “extreme” amounts of alcohol – an incident the department initially described as a series of overdoses on potentially tainted drugs had.

Police initially reported that at least six men were sick or overdosed Saturday evening after consuming “a possible contaminated batch of cocaine” at a party, and that alcohol was also involved. This was based on the use of the overdose reversal drug Narcan, as well as evidence found at the scene and “initial information,” police said.

In Tuesday’s update, the department said it did not appear that fentanyl was involved. The five sick students “consumed extremely high amounts of alcohol and some had consumed drugs, which led to them becoming seriously ill,” police said.

Investigators seized cocaine at the scene, which they say is being tested.

Boulder police said five men were treated at the scene or taken to the hospital, and one of them – whose prognosis was initially “serious” – remained hospitalized Tuesday.

Neither local nor national representatives of the Kappa Sigma fraternity responded to The Denver Post’s requests for comment.

Kappa Sigma is among three “rogue” fraternities that are not affiliated with any of the established Greek regulatory organizations at the University of Colorado.

Greek life at CU has been in disarray since 2005, when the Boulder fraternity — under scrutiny following the alcohol-related hazing death of Lynn “Gordie” Bailey the year before — left campus after refusing to enter into a delay agreement of the rush to sign by the spring of each year and have caretakers who live in the house.

The split gave rise to the independent Interfraternity Council on the Hill — a student-run oversight organization now led by general counsel Michael Smith.

The council is made up of more than 20 fraternity chapters in Boulder with nearly 2,500 members, Smith said.

CU Boulder reinstated its own fraternity council in 2015 and today has 10 active affiliated fraternities that have agreed to the university’s oversight.

Kappa Sigma was part of the Interfraternity Council on the Hill until about five years ago, Smith said. Kappa Sigma hosted parties that violated IFC on the Hill’s risk management rules, Smith said, leading to the split.

“They left the IFC after a series of events led them to appeal to our Judiciary Committee,” Smith said. “They suffered severe punishments and instead of being held accountable, they chose to leave.”

Sigma Pi and Phi Kappa Tau fraternities also do not belong to IFC on the Hill or the CU Fraternity Council. Instead of an oversight organization, Smith said, fraternity alumni are expected to oversee what he called “rogue houses.”

“Their graduates are much more concerned about the property than they are about their children,” Smith said, referring to Kappa Sigma’s 27-bedroom fraternity house at 1100 Pennsylvania Ave.

Nicole Mueksch, a spokeswoman for CU Boulder, said the university cannot prevent the existence of independent organizations or engage with them in student conduct and conflict resolution processes.

“However, it is important to note that all CU Boulder students are subject to our Student Code of Conduct, including students involved in unaffiliated organizations,” Mueksch said. “CU Boulder has processes in place, including the Student Conduct Resolution, to address incidents in which students or recognized student organizations are alleged to have violated university policies.”

CU Boulder’s Division of Student Affairs, Counseling and Mental Health Services and the Office of Victim Assistance are communicating with and providing support to those directly affected by the overdose incident, Mueksch said.