Iranian security personnel grappled with students at a top Tehran university overnight amid anti-government rallies.
Many Sharif University of Technology students were reportedly stranded in a ringed parking park.
One video showed schoolchildren fleeing gunfire.
Three weeks ago, anti-government demonstrations began following the death of a morality police detainee.
Ayatollah Ali Khamenei called Mahsa Amini`s death "bitter" and "heartbreaking" in his first public remarks.
He called the statewide rallies "riots" and "organized" by the U.S. and Israel "with the cooperation of few disloyal Iranians overseas."
Ms. Amini, a 22-year-old Kurdish lady, went into a coma after being accused of infringing a headscarf ban in the capital. Three days later, she died.
Her family says cops hit her head with a baton and a car. Police said she had "sudden cardiac failure" and was not mistreated.
Protests began during her burial on 17 September and have become the biggest unrest in recent years.
