Snipers fire at the demonstrators and a map of the conflict. Credit:AP Instantly, a single crack rang out, felling him. Two men ran, hunched over, to drag him back to a side street and the motorcycle. The soldiers allowed them to leave the zone with their critically injured friend, but they will not be allowed back. This is how the battle for Bangkok will be fought over coming days. Street by street, inch by inch, casualty by casualty. Scenes like this are being played out across the centre of the city, as troops slowly squeeze in on the fortified camp that has been held by anti-government Red Shirt protesters for weeks. The Red Shirts have not yet lost any territory to the army, but the government says it is prepared to wait them out, starving them of food, water, power and contact with the outside world.

The Red Shirts are determined to fight back. After two days of porous roadblocks which allowed supplies and extra Red Shirts supporters in, the army has put up barricades and strung razor wire across all roads leading to the protest camp. There are few ways in now. Already there are reports the Red Shirts are running short of food and of fuel. Scrambled mobile phone signals are making communications difficult, and the weariness of constant fighting is taking its toll. Despite the suffering, or perhaps because of it, the leaders on both sides remain resolute. The Prime Minister, Abhisit Vejjajiva, has appeared on every Thai TV channel promising to ''push forward'' with his plan to have the army forcibly remove the protesters, while Red Shirt leaders have vowed to fight to the end.

But on the streets, there is fear. Fear is in the eyes of the Red Shirts' guards standing defiantly, but nervously, at the fortified entrance to the camp. Full of bravado, Annan demonstrates his slingshot, pulling the rubber back and forth, aimed at a sniper, real or imaginary, in a nearby building. At his feet is a pile of rocks and lumps of concrete to hurl at oncoming troops. In his back pocket is a homemade rocket launcher fashioned from bamboo and scrap metal, to shoot fireworks at soldiers and police helicopters. They are a feeble riposte to the rifles and M-16s of the soldiers crouched behind sandbags and razor wire a few hundred metres away. The barricade behind which Annan stands, built up over weeks of protest, is a enormous wall of tyres and sharpened bamboo staves, four metres high. It reeks of petrol. Expecting troops to march on them any day, the Red Shirts have filled their barricades with fuel, ready to burn their city down before they give it up. ''We are getting killed. We are all scared to get killed, but we stay.'' But fear is written, too, on the faces of the troops on Rama IV Road, at the southern end of the Red Shirts' zone. Over loudspeakers, they plead with protesters for peace. ''We are the people's army. We are just doing our duty for the nation. Brothers and sisters, let's talk together.'' There is little hope of that.

In the late afternoon on Ratchaprarop Road in Din Daeng, in the north of the city, doing their duty includes firing live ammunition at anyone they see on the street. The army has designated it a ''live-fire zone'' because it is an entry point to the city for Red Shirt supporters from the north-eastern provinces. Four soldiers huddle behind a telephone box, signalling anxiously to colleagues further back up the road. As a petrol bomb lands with a ''whump'' in the middle of the road, three of them scurry back to the safety of a street corner while one remains to provide covering fire. He quickly retreats too, after firing a half a dozen rounds towards the mass of protesters. Soon it is dark. Nightfall comes quickly in this part of the world, making the city, scarcely possible though it is, even more menacing. The no man's land between the Red Shirts' fortifications and the soldiers' lines is completely blacked out, and eerily empty. Leaving the Red Shirts' area for relative safety outside the conflict zone, a small knot of protesters crouch in darkness on the corner of Ploenchit and Wireless roads. One tells the Herald: ''No light. Sniper, sniper. Up high. Shoot.'' We are forced to ride a motorbike, creeping along the edge of empty streets, holding a helmet over the headlamp to black it out of view of those soldiers in the buildings surrounding.

These streets, which house some of the most exclusive addresses in Bangkok, usually teem with activity 24 hours a day. Tonight, they are strewn with rotting garbage, but deserted of people. The only noise is distant gunfire and explosions, all too regular, coming from other parts of the city. Half an empty kilometre ahead are the lights of the army roadblock and the rest of the city beyond. Loading Thousands of Thais spend hours just outside the conflict zone, unable to see much beyond the smoke and the barricades, and unable to hear anything except for the volleys of gunfire. From a distance, they watch their city descend into war. As the Herald passes, one woman yells hysterically at the impassive soldiers manning the roadblock: ''They are killing us, they are killing us. We are Thais too. Why do they kill us?''