Automatic gunfire echoed in the Iranian capital early Saturday as hundreds of pro-government followers, some armed with Kalashnikov rifles, attacked groups of people demonstrating against clerical rule. In the most serious violence since the U.S.-applauded pro-democracy protests began four days ago, witnesses also reported seeing hard-line vigilantes pulling young women out of cars and beating them with sticks. Police stood by as hundreds of militiamen, who wear no uniforms and are fiercely loyal to Iran's leaders, manned checkpoints and roared around on motorbikes brandishing batons and chains. By 3:30 a.m. (7 p.m. EDT on Friday) there were no signs of protesters on the streets of the capital. Analysts say the protests, while small, reflect widespread frustration among Iran's mainly young population and are likely to continue in the run-up to the July 9 anniversary of violent student protests in 1999. Clerical leaders have accused the United States of stirring up unrest in Iran. Supreme Leader Ayatollah Ali Khamenei, who has the last word on all state matters said this week the authorities would show no mercy for "mercenaries of the enemy." Washington, which accuses Iran of building nuclear weapons and sponsoring terrorism, has hailed the protests which drew up to 3,000 people on previous nights. **BATONS AND CHAINS*** The militiamen jumped out of pick-up trucks and off motorbikes. Most were armed with batons and chains but a few carried Kalashnikovs. "I heard three single shots and then a burst of automatic gunfire, but I couldn't see where it was coming from or what it was aimed at," the correspondent said. He said he had heard two other bursts of gunfire and saw vigilantes beating one youth with chains and sticks. While venting most of their anger at unelected clerics who wield ultimate power in Iran, the protesters have also lambasted moderate President Mohammad Khatami. They accuse him of failing to deliver promised reforms after six years in power. In a tense atmosphere in central Tehran, Islamic militiamen probably from the Basij volunteer force tied to Iran's Revolutionary Guards, manned checkpoints and looked carefully into vehicles circling the streets around the university campus. "They pulled some people out of their cars and beat them with their fists and sticks. Even young girls were beaten," a photographer at the scene said. "I've seen at least 10 injured people. One man had a knife wound," he added. One U.S.-based Iranian exile satellite television channel reported clashes were also taking place in the central city of Isfahan. That could not immediately be confirmed. People in the bumper-to-bumper traffic around the university clapped and honked horns in unison in a show of support for the protests. They were quickly silenced by scores of vigilantes brandishing sticks. Inside the campus a few dozen students could be seen making victory signs with their hands. Trees and shrubs along one side of the campus were on fire. **PHOTO CAPTION*** Iranian motorcycle police leave their staging ground to quell riots at Tehran University June 13, 2003. Protests against clerical rule continued in the Iranian capital for a third night Friday. (Morteza Nikoubazl/Reuters)