Cairo, (Agencies): Bursts of heavy gunfire blazed Cairo's Tahrir Square, the epicenter of the protests against Mubarak, before dawn on Thursday, killing six people and wounding over 800 during clashes between supporters of Egyptian President, who is said to have misruled for almost 30 years, and Opposition protesters.

Thousands of supporters reached the square on horses and camels and launched attacks on protesters. The army had sent tanks and a helicopter to the square in anticipation of turmoil, but reports said they did not intervene in the matter, neither did the police act to preserve peace.

The opposition protesters were fired upon from a bridge near the square, killing three people on the spot, to bring the death toll to six in the last 24 hours.

The protesters refusing to quit from the Tahrir Square, which has become a hub of 'Down Mubarak' campaign, were fired upon at 4 am this morning and opposition spokesman claimed that violence was being unleashed by a force of paid thugs and plain clothes police to crush an unprecedented nine-day-old movement.

Witnesses reported at least three bodies being carried away in ambulances and said gunfire rained into the square from at least three directions and that the military deployed heavily did not intervene.

Pitched battles were also reported between pro-and anti-Mubarak groups for the control of a high vantage overpass leading to the square.

A few scribes were attacked by some protesters in the turmoil, but eventually managed to escape without serious injuries.

The Egyptian opposition has dismissed a promise by Mubarak to step down when his term of office ends in September, saying they want his immediate resignation.

"Egypt rejects what foreign countries propose. These countries assume the right to speak in the name of the Egyptian people and to voice demands of certain forces. The government of Egypt and its people view this as unacceptable," said Hossam Zaki, a spokesman for the Egyptian Foreign Ministry.

The United States, France, Britain, Turkey as well as the European Union called on Mubarak on Wednesday to start the process of transferring power in the country.

Transition of power must start: US

Toughening its stand against embattled Egyptian President Hosni Mubarak, the US has said the transition of power in the Arab State "must start now" and asked its new Vice President Omar Suleiman to probe the violent attacks on demonstrators by pro-regime activists.

 "A transition of power must start now," White House Press Secretary Robert Gibbs said at his daily news conference on Wednesday. "The people of Egypt need to see change."

82-year-old Mubarak, a close ally of the US who has been in power since 1981, is facing the greatest challenge to his autocratic regime in the wake of the protests which began on Tuesday last week.

Noting that US President Barack Obama has also called for immediate beginning of an orderly transition in Egypt, Gibbs said: "The administration believes that President Mubarak has a chance to show the world exactly who he is by beginning this transition that is so desperately needed in his country and for his people now. Gibbs' remarks indicated that the White House now clearly wants Mubarak to leave his post.

Also, Secretary of State Hillary Clinton telephoned Egyptian Vice President Suleiman, a longtime US ally, last evening and asked him to hold accountable those responsible for violent attacks on pro-democracy protesters.

Their telephonic conversation came as supporters of Mubarak fired at anti-government protesters in the Egyptian capital's Tahrir Square, killing six people.

Clinton called Suleiman to convey that the violence was a shocking development after many days of consistently peaceful demonstrations.

212 more Indians return

A third batch of 212 Indians stranded in Egypt, which is in the midst of a political upheaval, arrived in Mumbai early on Thursday in a special flight. Air India flight AI-160 landed with the Indians at 5.30 am, an official said.

This is the third flight to Mumbai in Air India's efforts to bring back the Indians trapped in Egypt. Earlier, two flights carrying 320 and 280 passengers respectively arrived in this city.

Air India flew a Boeing 747-400 from Mumbai to Cairo to bring the stranded Indians late on Wednesday.

The airline had made it clear that though it was carrying a humanitarian mission, it would charge the passengers Rs 45,000 each to cover the costs of operations.