Supporters and opponents of Egypt’s Islamist president battled in the streets near Tahrir Square on Friday as an Islamist rally demanding a purge of the judiciary devolved into violence.

The rally centered on a contentious aspect of the country’s deep political polarization — the courts. Islamist backers of President Mohammed Morsi say the judiciary is infused with former regime loyalists who are blocking his policies, while opponents fear Islamists want to take over the courts and get rid of secular-minded judges to consolidate the Muslim Brotherhood’s power.

But beyond the specific issues, the scenes of youths from both sides waving homemade pistols and beating each other with sticks illustrated how entrenched violence has become in Egypt’s political crisis. In recent weeks, several marches and rallies by the country’s various camps have devolved into street battles, fueling the bitterness on all sides.

Thousands of Morsi supporters — mostly backers of the Muslim Brotherhood and Islamist hard-liners — held rallies Friday outside the High Court building in Cairo and in the coastal city of Alexandria, demanding the “cleansing of the judiciary.”

The marches appeared aimed at presenting Islamists’ actions on the courts as a popular “demand of the revolution.” Islamist lawmakers who dominate the legislature have announced plans to begin debating a bill regulating the judiciary, presenting it as aimed at ensuring the independence of courts they contend are dominated by supporters of ousted leader Hosni Mubarak.

But opponents believe the Islamists aim to remove judges and install new ones who support their agenda. In an interview with a Kuwaiti newspaper this month, the former head of the Brotherhood, Mehdi Akef, called the judiciary “sick” and “corrupt” and said a new law could force out 3,500 of Egypt’s approximately 13,000 judges and prosecution officials by lowering the retirement age to 60 from 70 — though it remains to be seen if lowering the age will be in the final bill.

“Go for it Morsi and we are behind you. Cleanse the judiciary,” thousands of Islamists chanted outside the High Court building. Some, mainly followers of ultraconservative cleric Hazem Abu Ismail, waved black Islamic flags.

As some Islamists moved toward Cairo’s Tahrir Square, they were met by anti-Morsi youth a few blocks from the square, some of them in black masks. It was not clear who started the clashes, but it led to both sides pelting each other with stones and firing gunshots. One bus was seen set on fire. The sound of birdshot cracked through the air in the clashes, and tear gas was fired — even though there were no police nearby.

Some of the masked youths and Islamists were seen with homemade pistols. Others wielded iron bars and tree branches and broke up street pavements to throw the chunks of asphalt and concrete. More than 80 people were injured, according to the state news agency MENA.

Amid the battles, Islamists were seen dragging rivals to the ground and beating them. In one case, they beat a protester then shoved him into an ambulance, forced the ambulance workers out and drove off in the vehicle.

Ahmed Hamdi, a Muslim Brotherhood supporter at the scene, blamed the anti-Morsi protesters for the violence, calling them “thugs” and saying they set the bus on fire.

“The whole story is they see that Islamists are now in power. They can’t swallow this, that Islamists rule them. It’s a battle with the old regime,” he said.