CAIRO // In the north-eastern corner of Tahrir Square, Ahmed Maher stands next to a barricade made up of burnt-out vehicles, sheets of scrap metal and just about anything else that the protesters could get their hands on.
The 22-year-old business student is just one of hundreds of men - young and old, rich and poor - now standing guard at the square's thoroughfares and entrances.
Since mobs loyal to President Hosni Mubarak violently stormed the square on Wednesday, they have become the self-appointed defenders of the anti-government protesters.
"We are here to defend the people until Mubarak is gone," Mr Maher said. "But we don't start fights. That's Mubarak's thugs, his policemen."
The barricades yesterday enveloped tens of thousands of Mr Mubarak's detractors inside the square - separating them from the president's loyal secret police and political sympathisers.
At a moment's notice, the guards are ready to hurl a barrage of rocks and stones at charging pro-Mubarak mobs. They have placed piles of rubble and broken concrete at some of the sealed-off roads leading to the square. As a deterrent, some of the bigger rocks are brandished by the men at the most dangerous barricades.
By standing between the pro-democracy demonstrators and the pro-Mubarak mobs, they see themselves as the guardians of Egypt's uprising.
In doing so they have placed themselves beneath barrages of gunfire, rocks and Molotov cocktails.
When pro-Mubarak men edge closer to the demonstrators, they are chased off by dozens of the men holding rocks and truncheons. Metre by metre, they push back their opponents in an urban turf battle designed to clear more of the city centre of the presidents' men.
On Wednesday, the Egyptian military was unable - or perhaps unwilling - to stop the violent, pro-government mobs from storming the square. Yesterday afternoon, the anti-government protesters had taken it back.
After Wednesday's violence, Sayyid Hussein, a 20-something guard ing an alleyway leading into the north-eastern end of the square, no longer believes the military will protect the demonstrators.
"The army is with the government, 100 per cent," he said. "They are with Mubarak; they didn't help us! We have to defend ourselves!"
Others are not so hard on the soldiers surrounding the square. "The army isn't so strong, so we have to be ready to defend the people," said Sabah Ghouda, 23, a medical student who stood guard at a western entrance to Tahrir.
Even so, none of them are taking chances.
The guards have developed a crude but effective alarm system for when they spot approaching Mubarak supporters. On spotting their enemy, they slam bricks against the sheets of metal that form part of the barricades, sending out an ear-splitting warning.
Yesterday, as tens of thousand of supporters entered the square after Friday prayers, the guards carefully checked the protesters' IDs, and carried out random searches.
Another guard, also named Ahmed Maher, 22, who usually works as an electrician, said he found one Mubarak supporter hiding a knife during a pat-down on Thursday.
"He could have stabbed many people if he came in," he said. "We have to be ready for anything, but we're not afraid."
As he spoke, dozens of fellow guards beat rocks against metal sheets and hissed away several pro-Mubarak men.
Mr Maher was unmoved.
"They've tried that a few times today. Every time, we show that we're more powerful than them," he said.
