Clashes erupted Friday near Muslim Brotherhood's (MB) headquarters in the Egyptian capital of Cairo between MB supporters and opponents, state TV reported.
Anticipating further clashes between the two sides, a dozen security and armored vehicles have been deployed around the headquarters in Moqattam district.
An eyewitness told Xinhua that clashes have just renewed as some protesters threw stones toward the security forces separating the two sides.
"Sound of gunfire was heard but the source and type are unknown, " the witness said. "The police forces did not respond to stone throwing and remained in their position to protect the headquarters."
About 15 ambulances are deployed in the streets around the headquarters, he said.
Over 20 political parties and movements, mostly liberals, including Al-Dostour Party and Free Egyptians Party, in addition to some 30 public figures, have called for staging a rally dubbed "Friday of restoring dignity" on Friday outside the MB headquarters.
Meanwhile, in Manial district of Giza, some anti-MB protesters broke into the headquarters of the group's political arm Freedom and Justice Party (FJP), according to state-run Al-Ahram Online news website.
Anti-MB protesters across the country have been demanding holding presidential election in September under full international supervision, sacking the current government and prosecutor-general, and drafting a new constitution to replace the newly-drafted "Islamist-dominated" one.