The Cornell University campus in Ithaca, New York, is seen in January.
CNN  — 

Cornell University has suspended all fraternity parties and social events after campus police issued alerts about an alleged sexual assault and at least four alleged incidents of drug-laced drinks at an off-campus location, university officials said.

The university said in a letter Monday to students that the incidents “reportedly occurred at off-campus residences affiliated with registered fraternities.”

The school’s interfraternity council made the decision to suspend parties and other social events voluntarily Sunday evening after an emergency meeting with staff, University President Martha E. Pollack and Ryan Lombardi, vice president of student and campus life, wrote.

“No IFC-affiliated social events will resume until student leaders and Cornell staff are confident activities can take place responsibly and safely,” Pollack and Lombardi wrote, adding that they “fully support this necessary pause.”

Cornell campus police issued a crime alert Friday about at least four alleged incidents of drug-laced drinks between September 24 and November 3, “in which students reported to have consumed little to no alcohol at an off-campus location but became incapacitated while attending parties.”

A second alert was issued Sunday after an individual reported to campus police that they were sexually assaulted between 2:30 a.m. and 4:30 a.m. while attending an off-campus event. The Ithaca Police Department is investigating the alleged crime, Cornell Police said.

CNN has reached out to the Ithaca Police Department for comment.

CNN’s Tavleen Tarrant contributed to this report.