MIDDLETOWN, Conn. -- Wesleyan University says 12 people were hospitalized -- two of them in critical condition -- with symptoms of overdoses of the drug known as "Molly."

CBS Hartford affiliate WFSB reports the overdoses happened at a party Saturday night at the Eclectic Society House, which is a co-ed group on campus. Police said they responded to multiple calls for help.

In an email to students and staff Monday afternoon, university president Michael Roth said 10 Wesleyan students and two visitors needed medical treatment after taking the drug. Molly, a stimulant psychoactive drug also known as MDMA, is a potent form of the illegal party drug Ecstasy.

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"The effects are extremely dangerous, and as of now, four students are in Middlesex Hospital in Middletown (we expect them to be released today) and four others are being cared for at Hartford Hospital," Roth wrote.

Police told WFSB that students may have received a bad batch of the drug. They're looking for more information about the batch, not only for their investigation, but to help doctors treat those affected. Anyone with information was urged to call police.

Eclectic Society House at Wesleyan University in Middletown, Conn. WFSB

Dean Michael Whaley, vice president of student affairs, said in a letter to the campus Sunday that one of the students, a sophomore, was in critical condition at Middlesex Hospital. Sunday evening, Middlesex police said two patients at Hartford Hospital had been elevated to critical condition, and two were in serious condition.

Whaley said university police and residence officials are investigating, along with police. He asked students to check on their friends.

Roth urged students, "Please, please stay away from illegal substances the use of which can put you in extreme danger. One mistake can change your life forever. If you have friends who are thinking about trying these kinds of drugs, remind them of the dangers. If you are aware of people distributing these substances, please let someone know before more people are hurt."

Students were concerned as the news spread through campus. "I just don't really know how to feel right now," Lisa Shepard told WFSB. "It's just very shocking."

"I hope this serves as an example in a way for other students to be more cautious and careful," said Olayinka Lawal, another student. "It can happen to anyone."

Molly has been blamed for numerous overdoses in the past, including the deaths of two concert-goers at the Electric Zoo music festival in New York City in 2013. In 2011, hospitals reported more than 22,000 MDMA-related emergency room visits, according to the Drug Abuse Warning Network.