Wesleyan University's president said Monday 10 students and two visitors to the school received medical treatment after taking a version of the party drug known as Molly on campus over the weekend.
President Mark Roth, in a letter to the university community, said eight of those affected on Sunday remained hospitalized Monday, but said four of them were expected to be released later in the day.
The other four were expected to remain at Hartford Hospital, where two were listed in critical condition after being flown from the school on Sunday. Two others had been listed in serious condition.
The hospital and the school both declined to provide updated conditions Monday, citing privacy concerns.
School spokeswoman Lauren Rubenstein also declined to provide details of the incident.
When asked if it was whether it was linked to rave music show on campus Saturday night, she would only say that was part of an investigation and she could not comment.
The show, at the school's Eclectic Society, featured DJs from New York who go by the name Swim Team. They did not immediately return an email seeking comment.
Molly is a term used to describe a refined and more powerful form of Ecstasy (MDMA) or other similar synthetic drugs. It can drive up body temperature and cause liver, kidney or cardiovascular failure.
"If you are aware of people distributing these substances, please let someone know before more people are hurt," Roth wrote. "These drugs can be altered in ways that make them all the more toxic. Take a stand to protect your fellow students."
Middletown Police Chief William McKenna said his department was pursing information about a "bad batch" of the drug.
"Our first and foremost goal is to obtain information on the batch of Molly that was distributed to the students on the campus," McKenna said. "This information is critical in ensuring the recovery of those students affected."