Police have used tear gas against protesters who are now facing off with Central Security Forces on Qasr El-Aini Street near the headquarters of the Egyptian cabinet and the Ministry of Interior.
Meanwhile, a field hospital has been set up in nearby Tahrir Square to treat those who suffer breathing difficulties from teargas and other injuries.
Protesters commemorating the anniversary of last year's Mohamed Mahmoud Street clashes had faced off with the police in the northern vicinity of the Ministry of Interior through Nubar Street off Mohamed Mahmoud for two hours earlier on Monday evening.
Other roads leading to the ministry from Mohamed Mahmoud Street have been closed off for months by walls made of concrete blocks.
Rows of Central Security Forces and military police stood between the protesters and the ministry building, according to Ahram Online reporters on the ground.
In the evening hours, clashes erupted between protesters and police at the scene of the demonstration in central Cairo.
Stone-throwing between protesters and police took place intermittently on Youssef El-Guindy Street, off Mohamed Mahmoud Street, over a wall erected by the army last year that stands between both sides.
Tear gas canisters were fired by the police on Youssef El-Guindy Street, forcing protesters to fall back to Mohamed Mahmoud Street.
The sound of gunfire was heard, but it is unverified whether the sounds came from birdshots, rifles firing rubber bullets or live fire.
Motorcycles started ferrying wounded protesters to safety in scenes reminiscent of last year's clashes.
Some protesters lobbed molotov cocktail bombs prepared on the scene at security forces, according to Ahram Online reporters.
Later in the evening, the Ministry of Interior issued a statement saying that three officers and five soldiers have been injured in the clashes.
Protesters had also blocked the entrance to the street from Tahrir Square with a sign declaring that "the Muslim Brotherhood isn't allowed to enter."
Heeding the call by fifty political parties and movements, several thousands of protesters had started to gather in Mohamed Mahmoud Street since 4pm.
At the beginning of the demonstrations, protesters chanted against retired field marshal Mohamed Hussein Tantawi – the interim ruler of Egypt during the clashes of 2011 – as well as against the police and Egypt's current rulers, the Muslim Brotherhood.
Protesters carried flags of Ultras, hardcore football supporters, and the April 6 Youth Movement as well as placards emblazoned with the faces of Egyptians viewed as revolutionary martyrs, like Mina Daniel and Azhar preacher Emad Effat.
University students came from Cairo University to Tahrir Square in mid-afternoon to mark the anniversary.
The Popular Socialist Alliance Party, April 6 Youth Movement, Constitution Party, Maspero Youth Coalition, the Revolutionary Socialists, the Popular Current, and Shayfenkom (We Are Watching You) also took part in the memorial event.
Last November, around 47 protesters were killed during four days of street clashes that erupted after the Central Security Forces tried to violently disperse a peaceful sit-in in Tahrir Square.
The commemoration is planned to continue until Friday. Each day activists will march from a different location to Tahrir and Mohamed Mahmoud Street.
The Second Revolution of Rage group had called for a march on Monday from the school in Sayyida Zeinab attended by one of the slain protesters to Mohamed Mahmoud Street. A second protest took off from Qasr El-Nil bridge to remember those who suffered eye injuries duing the clashes.