Police at the University of Arizona deployed "chemical irritant munitions" to clear pro-Palestinian protesters early Wednesday morning.
Campus police had ordered the crowd to disperse immediately from what they deemed an "unlawful assembly."
When they refused the police advanced in the area of University Blvd & Park Ave. shortly after midnight.
Videos posted on X showed violence as a line of officers attempted to push the protesters back.
At 2 a.m. the school announced: "University of Arizona President Robert C. Robbins has directed University officials and the University of Arizona Police Department, to immediately enforce campus use policies and all corresponding laws without further warning.
The police immediately deployed the chemical irritant at the protesters.
They issued an "all clear" less than a half hour later. They did not announce any arrests in connection with the violence.
Violence broke out at protests across the country late Tuesday and early Wednesday.
On UCLA, dueling groups of protesters clashed late on Wednesday. Protesters got into fights and some used sticks to attack each other.
They happened at a tent encampment built by pro-Palestinian protesters. They had built plywood around their protest site. Pro-Israeli counter-protesters tried to pull the barricades down and that's when the confrontations started.
In New York on Tuesday evening, the NYPD raided Hamilton Hall on the Columbia University campus to disperse anti-Israeli protesters who had taken over the building about 12 hours earlier.