Clashes intensified Wednesday night outside the presidential palace in Heliopolis between supporters and opponents of President Mohamed Morsy. The Health Ministry denied reports that one person was killed in the fighting.

Eyewitnesses told Al-Masry Al-Youm that security forces assaulted the anti-Morsy protesters and arrested dozens of them.

Marghany Street, the main front line, is the scene of a warzone, with fighting spilling over onto Khalifa al-Maamon. Eyewitnesses there say Morsy supporters outnumber opponents.

The two sides are fighting with no security intervention, though the area has some military police posts, which are now empty. Al-Masry Al-Youm reported that Central Security Forces are making their way to the scene and attempting to separate clashing protesters.

The Interior Ministry said in a statement that the CSF are trying to establish a cordon between the protesters and the presidential palace, but clahes are ongoing in the area.

Eyewitnesses have reported use of pellets and birdshots, as well as consistent sounds of gunshots. The Health Ministry has reported 18 injuries, and numerous protesters are suffering from head injuries as a result of stone throwing.

Health Ministry spokesperson Ahmed Omar said that the injuries varied between cuts, bruises and suspected fractures, and that the patients would be released as soon as they are stable.

Some residents in the area attempted to flee into their houses, but they fear fires may start.

State-owned Al-Ahram newspaper reported that the clashes started when Morsy’s supporters threw Molotov cocktails at members of the ultras, and targeted them with birdshots. The state mouthpiece added that the ultras responded by throwing stones and fireworks.

Security forces and ambulances were almost absent from the area, the paper added.

The privately-owned ONTV satellite channel reported that the clashes are “violent.” The channel’s correspondent said that dozens have been injured in the clashes.

Hundreds of Muslim Brotherhood members and supporters of Morsy fled toward the presidential palace, chanting, “Morsy.. Morsy,” while masses of opposition protesters continued their sit-in before th e palace, Al-Masry Al-Youm reported.

Clashes between the two sides had stopped after protesters against Morsy set up barriers to secure their sit-in against supporters of the president, who were trying to remove their tents.  

Privately-owned TV channel Al-Nahar, in live reports from the scene, said that Morsy supporters boxed opposition protesters in from two sides, leading to scuffles.

The clashes come after both the Popular Current, led by former presidential candidate Hamdeen Sabbahi, and the Muslim Brotherhood called for rival demonstrations outside the presidential palace Wednesday, raising the specter of clashes between both sides. Anti-Morsy protesters had begun a sit-in the night before after holding a mass demonstration.

However, the Muslim Brotherhood Guidance Bureau announced on Wednesday that its members will also start a sit-in in front of the presidential palace until the constitutional referendum is successfully held.

The Brotherhood demonstrators will be there to support Morsy, and his decision to put the constitution for a referendum, according to a statement, which also called for a “general mobilization” among youth in support of the sit-in.

Freedom and Justice Party Vice President and presidential adviser Essam al-Erian said Wednesday, "Egyptian people will flood to squares in all governorates, especially at the presidential palace, to protect legitimacy."

Erian added that "the people are capable of imposing their will and party members are in the forefront," in the event that state agencies remain dominated by what he claimed were former regime supporters, while also saying that the president would not back down from his decision.

The Brotherhood's earlier call for protests, with anti-Morsy protesters already staging a sit-in outside the palace, drew condemnations and warnings from opposing political parties.

Former presidential candidate Amr Moussa, who is also chairman of the Congress Party, denounced the Brotherhood’s call for protests.

“Clashes with other protesters over differences in opinion will further heat up the situation,” Moussa tweeted on Wednesday.

The Constitution Party also warned of "dire consequences" for what it described asassaults on peaceful protesters in Tahrir Square and outside the palace.

"We are warning of dire consequences for mounting calls by figures affiliated with the Muslim Brotherhood and the Islamist current,” the party said in a statement, which claimed that the president’s supporters had called for massive protests “and even jihad.”

In a statement posted on the group's Facebook page, Brotherhood spokesperson Mahmoud Ghozlan said that the calls for demonstrations were meant to "protect the legitimacy after the brute infringements conducted on Tuesday by a group that thought they could shake legitimacy or impose their opinion by force."

Thousands-strong marches headed to the palace Tuesday night in protest of the president's rush to put the constitution up for a vote, as well as his constitutional declaration last month granting him broad powers.

Earlier on Tuesday, the website of state-run Al-Ahram newspaper quoted a Jama'a al-Islamiya source as saying that various Islamist factions will gather at the palace to support Morsy. The Muslim Brotherhood’s Freedom and Justice Party, the Salafi-oriented Nour Party and Jama'a al-Islamiya’s Construction and Development Party are among the groups that will participate, according to Al-Ahram.