Ammon News - (Al Arabiya with AFP and Reuters) - After millions of protesters flooded streets across Egypt, the country was locked in a tense standoff on Monday as demands for the resignation of Islamist President Mohammed Mursi remain stern, and the opposition plans its next moves.

At least 10 people were killed during Sunday’s protests and more than 600 wounded during clashes between Mursi’s supporters and opponents, according to Al Arabiya reports on the ground and medical sources.

Reuters news agency reported that five of the dead were shot in towns south of Cairo, one each in Beni Suef and Fayoum and three in Assiut.

Two more were killed by gunfire during an attack on the Muslim Brotherhood national headquarters of in a suburb of the capital, medical sources confirmed.

The demonstrations, which brought half a million people to Cairo’s central Tahrir Square and a similar crowd in the second city, Alexandria, were easily the largest since the Arab Spring uprising that ousted Hosni Mubarak in 2011.

Around 150 “thugs” attacked the building in the Moqqattam neighborhood with molotov cocktails, birdshot and stones, said Gehad al-Haddad, a spokesman for the Muslim Brotherhood.

The opposition National Salvation Front said protesters will remain in the streets until the fall of the regime.

A leading opposition figure told AFP on Sunday that Egypt’s army should intervene Mursi refuses to step down in response to calls from anti-government protests.

“The armed forces must act, because they have always been on the side of the people,” which “has expressed its will”, said Hamdeen Sabahi, who came third in the 2012 presidential election, running as a left-wing nationalist candidate.

Opposition leaders, who have seen previous protest waves fizzle after a few days in December and January, were to meet on Monday afternoon to plot their next move, Reuters news agency reported.

The Freedom and Justice Party, the political arm of the Muslim Brotherhood, also vowed that the pro-Mursi coalition will also remain in sit-ins to defend until opposition end their rallies.

As Egypt appeared deeply divided on Sunday with the escalation of violence, the office of the president said it was open for dialogue with the opposition.

“Dialogue is the only way through which we can reach an understanding... The presidency is open to a real and serious national dialogue,” presidential spokesman Ehab Fahmy said in a press interview broadcast by Al Arabiya.

Fahmy called on protesters to maintain “the peaceful nature” of their protest, describing anti-Mursi demonstrations as an example of free expression in Egypt.

Interviewed by a British newspaper, Mursi repeated his determination to ride out what he sees as an undemocratic attack on his electoral legitimacy. But he also offered to revise the new, Islamist-inspired constitution, saying clauses on religious authority, which fueled liberal resentment, were not his choice.