Egyptian police fire tear gas and live rounds in the air to disperse anti-government protesters in the capital Cairo on Saturday, as the country marked the third anniversary of the 2011 uprising that toppled former President Hosni Mubarak .
Security sources told Al Arabiya News Channel that aat least 33 Muslim Brotherhood supporters had been arrested in Cairo for attacking police forces.
Police broke up protests shortly after they began around a Cairo mosque, according to an Agence France-Presse correspondent.
The protesters included both Islamist supporters of ousted President Mohammad Mursi and activists who accuse Egypt’s army of hijacking the government.
A witness said that police also fired tear gas and birdshot at a crowd of secular liberal activists attempting to march toward Cairo's Tahrir Square.
The blast was sparked by what was described as a small "incendiary bomb" lodged on the wall of the police training center and exploded without causing any casualties, a police official told Agence France-Presse. It was thrown by an assailant, who later escaped, the official added.
The second blast was reported in Hadaeq al-Quba, a Cairo district. Details of this attack remain unclear.
Following a string of deadly bomb attacks a day earlier, Egypt on Saturday woke up to the third anniversary of the uprising on a tense note.
A series of bomb attacks in Cairo and clashes across the country on Friday left at least six people dead and wounded several others. In the most high-profile attack on Friday, a car bomb exploded at a security compound in central Cairo early in the morning and killed at least four people, including three policemen, security sources said.
Ansar Beit al-Maqdis, an al-Qaeda-inspired Egyptian insurgent group, claimed responsibility on Saturday for the four bombings the day before. In its statement, the group called for Muslims to stay away fom police buildings.
Rival political groups in the country are set to mark the 2011 uprising which ended in the overthrow of President Hosni Mubarak with planned protests across the country.
The Muslim Brotherhood has held regular protests since the military, led by Gen. Abdel Fattah al-Sisi, ousted Islamist President Mohammad Mursi last July.
The Anti-Coup Alliance, led by Mursi's Muslim Brotherhood, called in a statement for 18 days of protests beginning on Saturday, mirroring the 18 days of protests that led to Mubarak stepping down in 2011.
The 2011 revolt raised hopes of a stable democracy in the Arab world's biggest nation. Instead, relentless political turmoil has hit investment and tourism hard in Egypt.
The government has said extra security measures are in place for Saturday.
"We have a plan to secure all of this for the anniversary of the 25 January revolution," Egyptian Interior Minister Muhammad Ibrahim said.
He urged Egyptians not to be afraid to go to events marking the anniversary. However, earlier this week he warned supporters of the Brotherhood that any attempt to "disrupt" festivities will be dealt with "firmly."
Clashes in the capital and several other cities between Mursi supporters and security forces which killed 11 people also raised tensions in the biggest Arab nation.