A supporter of President Mubarak crosses out "Leave" and writes "We love you"

The battle for Liberation Square didn't start out so bad.

I was down on the street when it began, and I saw a young man in glasses, a pro-democracy protester, sitting on the curb having an impassioned discussion with an elderly man in a tattered sportscoat. I could make out just a bit of what they were saying - the younger man was complaining about a lack of money, the older man was railing against opposition figure Mohammed ElBaradei, whom he called "the American." They argued for a few minutes, but when it was over the older man grabbed the other and kissed him on the cheek. Both went their separate ways.

It was one of the rare moments of conciliation today in Tahrir ("Liberation") Square. Moments later, I saw a mob of pro-regime elements set upon two young women and their male friend as they tried to exit the square occupied by pro-democracy protesters. I went up to one of the women to ask her name and for an interview, but then she returned an insult shouted to her by an angry Mubarak supporter and the mob turned on them, chasing them down one of the side streets near the Egyptian Museum.

Sweat poured off the man's face; the women had real fear in their eyes. They pounded on the door of a hotel before someone let them in, but the crowd continued to bang on the door for several minutes, shouting, "Get out!" and "God is great!"

The fighting devolved quickly from there, of course. At midnight, after writing and watching the clashes for hours from my hotel balcony, I walked back down to the square, to the overpass where dozens of people were standing. Down below the pro-democracy group had set two cars ablaze and lined themselves up in a human barricade near the Egyptian Museum. They were holding some sort of makeshift shields, looking like citizen riot police.

I walked up to the bridge, trying to keep my head down, knowing these guys didn't like journalists, and saw some young guys carrying rocks bigger than their heads. One had a machete, several had sticks. They were perched on the overpass and exchanging petrol bombs with the pro-democracy group down below. The two sides were barely 100 yards apart, the guys on the bridge egging their opponents on. The mood seemed almost playful, like a bloody game of Capture the Flag. Suddenly the guys on the bridge turned and ran in my direction, back down the bridge. A petrol bomb had landed near them and something had caught fire. Suddenly well aware of my camera and American passport in my pocket, I turned and ran too, down the bridge and back toward my hotel.

At 5:30 a.m. I awoke to a call from my editor in Washington and went back onto my balcony to see the vehicles still smoldering, the protesters still banging on metal barriers, defiantly holding their ground. Bursts of automatic gunfire could be heard, and the occasional single shot. It was hard to tell where they were coming from, but wires were reporting that snipers were firing from rooftops. I suddenly decided the balcony was not the place to be.

This was the scene at about 9 a.m. this morning - the protesters holding onto corrugated tin shields, tanks having moved in to separate them from pro-Mubarak forces. You can hear the chants, they seem louder today. Friends in other parts of Cairo say that both sides are busing in reinforcements.