Tensions flared Sunday across Iran as anti-government protests reignited at major universities and in the streets of Tehran, with reports of tear gas and shots fired in the capital.

Students gathered in Tehran and the northeastern city of Mashhad to mark 40-day memorials for those killed during January’s nationwide anti-government demonstrations before violence broke out.

Ali Safavi, a member of Iran’s Parliament-in-Exile, the forceful response by authorities.

Security forces reportedly fired tear gas at crowds of demonstrators, many of them young people. 

At other locations, the protesters also confronted groups of pro-regime demonstrators.

Reports from opposition sources indicated that shots were also fired as security units attempted to disperse gatherings that had spilled beyond campus grounds into surrounding streets.

Nighttime mobilizations also continued for a second time, with large-scale protests reported across several campuses.

The clashes marked one of the most visible displays of unrest since January’s crackdown and came as Iran faces a potential military strike by the U.S. and amid ongoing talks to negotiate over Iran’s nuclear program.