MANHATTAN – The New York City Police Department is investigating reports that students were attacked with a chemical spray last week during a pro-Palestinian protest at Columbia University, causing several people to seek medical treatment.

The spraying student described occurred during a student-led divestment protest at the Ivy League campus Friday afternoon against the ongoing war in Gaza. The protestors said they sprayed an unknown substance in the air that caused a foul odor. The chemical caused some students to experience nausea and burning eyes. The Columbia Spectator, the student newspaper, first reported about the incident at a “divestment now” rally on the university’s library steps.

A woman reported the incident to police on Saturday, the day after it happened, and five others reported the attack on Sunday, NYPD said in an email on Tuesday. No arrests have been made.

On Monday, Columbia’s interim provost, Dennis Mitchell, wrote in a campus email that the university banned the people alleged to have perpetrated the chemical attack. He didn't identify whether the suspected assailants were students, and the university declined to provide more details.

Mitchell said in the email that demonstrators had reported being sprayed with “a foul-smelling substance” that required students to seek medical treatment. The university is working with NYPD, which is leading the investigation into “what appear to have been serious crimes, possibly hate crimes.”

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On Sunday, the Columbia Department of Public Safety said it was working with NYPD and federal officials to investigate the incident.

The FBI declined to comment on Tuesday. The Manhattan District Attorney's Office did not immediately respond to questions.

Some city officials spoke out about their concerns in social media posts.

"No student should be afraid to express themselves on campus or elsewhere in our city," City Councilmember Shaun Abreu said on X Monday.

Manhattan Borough President Mark Levine, who has previously spoken in support of pro-Israeli demonstrators, denounced the act on Threads, a social media website.

"Violence against protestors is despicable and unacceptable," he said on Tuesday. "The perpetrators should face serious consequences."

According to the Spectator, three students said the weapon was “skunk,” a chemical used by Israeli military against demonstrators in the Palestinian territory of the West Bank.

In a statement on Monday, Students for Justice in Palestine and Jewish Voice for Peace, student groups based at Columbia, said eight students had been hospitalized and dozens more sought urgent medical attention. They described the assailants as former Israeli military soldiers, a claim USA TODAY could not independently verify.

The student groups called on the university and U.S. elected officials, who had previously come to defend Israeli supporters on college campuses, to investigate the incident amid rising attacks against Palestinian, Arab and Muslim American students. The university reportedly chided the student groups for holding an unsanctioned event that violated school policies intended to ensure adequate safety measures are in place.

“The double-standard is clear,” the joint statement said. “Who will protect students who are advocating for safety and freedom for Palestinians.”

Columbia had previously cut funding or the ability to host events for Students for Justice in Palestine and Jewish Voices for Peace for the academic year.

Zachary Schermele contributed to this report.