Four Wesleyan University students were arrested Tuesday in connection with the hospitalizations of 12 people who took a party drug known as Molly over the weekend.

The students were arrested on drug charges, police said. The students were also suspended from the Connecticut university.

The students were charged with possession of a controlled substance, illegally obtaining or supplying drugs, selling a hallucinogen and possession of drug paraphernalia.

Wesleyan president Michael Roth said the school takes drug distribution allegations seriously and is cooperating with authorities.

Eleven students and two visitors received medical attention after taking the drug at a rave music show. The school became aware of the incident Sunday morning after students were seeking treatment at a hospital near campus.

Police are trying to find out who supplied the Molly and have searched locations in and around campus. Authorities are also trying to figure out the different types of chemicals used in the batch that was handed out at the party. The batch may have been bad, causing the hospitalizations.

"This particular batch may have had a mixture of several kinds of designer drug chemicals, making the health risks unpredictable and treatment to combat the effects complex and problematic," he said.

The arrested students were identified by police as Eric Lonergan, of Rio de Janeiro; Andrew Olson, of Atascadero, California; Zachary Kramer, of Bethesda, Maryland; and Rama Agha Al Kakib, of Lutherville, Maryland.

Molly is a term used to describe a refined form of Ecstasy, a synthetic drug also known as MDMA. It can drive up body temperature and cause liver, kidney or cardiovascular failure.

Dr. Mark Neavyn, chief of toxicology at Hartford Hospital, said users who believe they are taking Molly are often receiving different kinds of designer drugs, with ranges of purity and potency making the health risks unpredictable. He said testing is underway to confirm what drugs the Wesleyan patients took.

"When we see these people in the emergency department and they claim to have taken Molly, we don't pay attention to that word anymore. It's so commonly not MDMA, we just start from square one and say it's some sort of drug abuse," Neavyn said.

Wesleyan university has seen this type of incident in the past. School health officials sent a campus-wide email Sept. 16 saying students had been hospitalized after taking Molly the previous two weekends. Students were urged to visit the school’s health center if they had questions or concerns.

The Associated Press contributed to this report