Updated

Masked men briefly blocked trains at a central Cairo subway station Monday as Egyptians commemorated the second anniversary of autocrat Hosni Mubarak's ouster with angry protests directed at his elected successor.

A dozen other protesters blocked traffic on a main flyover in Cairo. And hundreds rallied outside the office of the country's chief prosecutor demanding justice and retribution for protesters killed in clashes with security forces after Islamist President Mohammed Morsi took office last summer.

Egypt has been gripped by political turmoil since Mubarak's ouster on Feb. 11, 2011 in a popular uprising sparked largely by widespread abuse at the hands of state security agencies. After he stepped down, Mubarak was replaced by a ruling military council that was in power for 17 months. The rule of the generals was marred by violence and criticism directed at the council for mismanaging the transitional period.

Morsi won the first free and democratic elections in June by a small margin. But he and his Muslim Brotherhood, which rose to be Egypt's most powerful political group, are now facing the wrath of Egyptians who say few of their goals when they toppled Mubarak have been realized.

Protesters are particularly angry over continued violations and heavy handedness of security services, claiming little has changed since the Mubarak era. Many accuse Morsi and the Brotherhood of trying to monopolize power and ignoring the demands of the secular and liberal groups who were the backbone of the uprising.

Government opponents planned to march to Tahrir Square, the epicenter of the uprising which has been sealed off by protesters since November. Other marches were heading to the presidential palace.

The protesters are demanding the amendment of the country's new constitution. They claim the Islamists rushed the charter through the approval process despite disagreement with the opposition, which says some clauses undermine freedoms of expression and belief, and chip away at women rights.

The protesters are also demanding a new Cabinet, accusing the current government of being ineffective and failing to rein in police abuses or institute economic reforms. One of the most heated issues for protesters remains the lack of justice for those behind the deaths of hundreds of civilians during protests against the state.

Morsi and his supporters have repeatedly dismissed the opposition's charges, accusing them and Mubarak supporters of trying to topple a democratically elected president.

An increasingly violent wave of protests has spread outside of the capital in recent weeks as political initiatives failed to reign in the anger.

The recent explosion of violence began on the second anniversary of the start of the uprising on Jan.25.

It accelerated with riots in the Suez Canal city of Port Said by youths furious over death sentences issued against local soccer fans over a bloody stadium riot a year ago. Around 70 were killed in this wave of clashes.

Before the major protests planned for the Monday anniversary began, a group of masked men stopped trains in a main Cairo subway station in Tahrir Square briefly as a way to escalate their pressure on Morsi to respond to their demands.

They stood on tracks and witnesses said they scuffled with some passengers angered by the obstruction of traffic, pelting each other with rocks.

A security official said the metro police tried to stop the fighting. Birdshot was fired in the subway station, injuring some. The official spoke on condition of anonymity because he was not authorized to speak to the media and said he didn't know who was behind the shooting.

Scores of activists from April 6, one of the key groups behind the uprising, rallied outside the office of the chief prosecutor, whose appointment by Morsi garnered wide criticism as a violation of the judiciary's independence.

They demanded retribution for the hundreds of protesters killed at the hands of security forces particularly since the election of Morsi. The protesters lobbed plastic bags filled with red liquid at the office, symbolizing the spilled blood of civilians.

They chanted: "Hey, appointed prosecutor, who will bring justice to those martyrs?"

Protesters also locked shut the doors of the main administrative building for state services just outside the subway station at Tahrir Square, while others blocked traffic at a main bridge on the other side of town that leads to the presidential palace, standing in the road and burning tires.