Mark Birtell has never heard his mother cry until now. As he steers his motor boat through the dark, all he can hear on his mobile phone are heaving sobs. They form an apt backdrop to the melancholy scene before him - and a reminder of the pain Hurricane Katrina has wreaked on New Orleans, where the spirits of the dead may now outnumber those left behind. Amid the chaotic evacuation of survivors from the city, there is no way of telling whether Mr Birtell's Aunt Dot, Aunt Julie and Uncle Rob made it out of their homes in Chalmette, a hard-hit area in the parish of St Bernard. He is determined to find out, and his mother is begging him to try to get there. But he has been waylaid because of the pressing need to search homes en route. His own home is under water, but he has a mobile phone, a commandeered boat and some fuel he has salvaged from vessels drifting on the floodwaters. 'It's not theft. We're using what resources we have in the best way we know how,' he says. Mr Birtell has teamed up with three like-minded citizens - Floyd Simeon and his fiancee, Tuti Sheiban, and Ned Armand - who he met on the water. They have just ferried around 20 survivors to dry land after another team rounded them up from a neighbourhood on the other side of the railway tracks. They are operating simply by word of mouth. 'We're just a ragtag bunch of guys slogging around. We don't see any co-ordinated effort out there for search and rescue, and people are dying. They need us,' Mr Armand says. 'It was Floyd's idea. He got out of bed, smoked a cigar, ate some Fruit Loops and said, 'Guess what? We're going to go and help those people'.' It is dangerous work. The water is so high in the neighbourhood of Lakeview that the boats keep grinding across the roofs of cars, sets of traffic lights, trees and garden railings. Fish leap from the water and a squirrel scampers in confusion up and down the same tree branch, with nowhere else to leap because it is all water. Dr Sheiban points out the Lakeview Harbor restaurant, where the flood is now a metre below the guttering. 'They used to do a great steak sandwich there,' she says. Power cables that once criss-crossed the streets between telegraph poles are now at neck level, adding to the lethal assault course and forcing those on board to duck suddenly as they loom into view. Whirlpools of gas bubble up from ruptured mains. Mr Birtell and the others are travelling in two boats, in case one breaks down, and they are still out on the water at 9pm after working their way around various addresses looking, without success, for survivors. There is steam rising from the water - this neighbourhood is now just an extension of the Louisiana swamp - and coastguard, army and navy helicopters buzz overhead, sweeping their powerful searchlights back and forth through the waterlogged wasteland. Police, sheriff's deputies and military officials clad in combat gear with formidable arsenals in their boats and strapped to their waists weave across the water on unknown missions. Mr Birtell and his friends pull up to a house where a 90-year-old man has been reported stranded. After an hour-long slog to reach the address, they ram their boats through the front door to break it down before Mr Armand jumps and swims down the hallway. He emerges vomiting. There is no sign of the old man, but there is a putrid stench. The teams back away, hoping the smell is that of a rotting kitchen and that the owner may have been rescued earlier. Up on the railway embankment that crosses Canal Boulevard, boat crews have been passing survivors to one another, their vessels unable to go any further. After one boat brings them in, another ferries them to dry land, though there is no transport waiting for them. They are hungry and thirsty. There have been reports of shootings on the rail tracks - maybe looters on the prowl. 'There is no organisation. We are the organisation,' says Dr Sheiban. 'There was a bunch of 20-year-old kids from the National Guard up here keeping watch at one point, but they hadn't been given any ammo. Can you believe it?' A number of homes have windows open, with chairs or tables pulled up to the sills, or roofs with holes punched through them and ladders leading out where families scrambled in panic. Some took to boats, or waded and swam to higher ground; some have been rescued by helicopters; many are feared still trapped. Because there is no overall co-ordination of this search and rescue effort, volunteers do not know which homes have already been searched and which may still have people trapped inside. Simeon's shouts of 'Hello' bounce back off the black water unanswered. 'It's just the ghosts left now,' he says. 'It just looks like the end of the world out here.'