Leaders from the US, UK, France and Germany have urged Egypt's President Hosni Mubarak to avoid violence and enact reforms as protests continue.Vigilante groups in Cairo have set up checkpoints amid reports of widespread looting. A BBC correspondent says the streets are on the brink of anarchy.Mr Mubarak has appointed a vice-president as he struggles to regain control after five days of protests.It is now believed at least 100 people have died since Tuesday.US President Barack Obama met national security officials on Saturday to discuss the situation in Egypt.Afterwards, the White House said it would continue to focus on "calling for restraint, supporting universal rights and supporting concrete steps that advance political reform."There was a similar call from the leaders of Britain, Germany and France."We call on President Mubarak to avoid at all costs the use of violence against unarmed civilians, and on the demonstrators to exercise their rights peacefully," said Prime Minister David Cameron, Chancellor Angela Merkel and President Nicolas Sarkozy in a joint statement.Protests continue Despite a nominal curfew, Cairo's central Tahrir (Liberation) Square has remained filled with protesters into the night. Troops and armoured vehicles have been deployed but have not taken any action.But clashes between the protesters and the riot police have left at least 74 people dead since rallies began on Tuesday. About 2,000 people have been injured.Earlier, President Mubarak named intelligence chief Omar Suleiman as the first ever vice-president in his 30-year rule.Aviation Minister Ahmed Shafiq was appointed prime minister."Our people say to Mubarak: 'Mubarak, get out, get out and get away! We want to change you. We don't want new ministers. We want a new president," one demonstrator told the BBC.In many neighbourhoods, residents have formed committees to protect their properties from looting.The BBC's Lyse Doucet, in Cairo, says she has seen one local defence committee arming itself with hockey sticks, a metal exercise bar and a table leg.Looters rampaged through a number of upper-class neighbourhoods in Cairo, while in Alexandria there were reports of widespread looting of supermarket chains.Despite an impromptu guard made up of volunteers, at least two looters managed to get into Cairo's museum of antiquities, damaging some of the exhibits."They were able, these two people to enter the Cairo museum from the [roof] and they destroyed two mummies and they opened one case," said Zahi Hawass, secretary general of Egypt's Supreme Council of Antiquities.The UK has advised against all but essential travel to Cairo, Alexandria, Luxor and Suez.The US has issued warnings to its nationals to cancel non-essential travel to Egypt. A number of European countries have also advised against visiting the country.Cairo stock exchange will be closed on Sunday - a full trading day in the Middle East - because of the turmoil in the city.Mobile phone services were restored in Cairo on Saturday, but the internet remains down.The unrest in Egypt follows an uprising in Tunisia two weeks ago which toppled President Zine al-Abidine Ben Ali after 23 years in power.The Tunisian upheaval began with anger over rising food prices, high unemployment and anger at official corruption - problems which have also left many people in Egypt feeling frustrated and resentful of their leadership.Source: BBC