They have found air pockets in the rubble, but no more survivors

Rescue Effort

For the first time, rescue workers at "ground zero" have penetrated to the lowest level below the ruins of the twin towers. They dropped down into the commuter railway station 80ft underground and found some voids ­ air pockets in the rubble ­ but no one alive.

The teams of hard-hatted workers, firefighters and police officers carefully avoided the collapsing gaps in the 150ft heap of rubble where survivors might be trapped. Using power saws, crowbars and their hands in addition to hydraulic cranes and excavators, they worked their way through.

The latest statistics show the enormity of the task. Only 190 people are confirmed dead and 115 identified, with the number missing now at 4,957. Nearly one million tons of rubble; only 25,000 tons ­ less than 3 per cent ­ had been cleared.

Only five people have been discovered alive and no one has been found since Wednesday. The mountains still stand several storeys tall and the chances of pulling out anyone else alive now seem remote.

"People have survived buried in rubble for 10 days in earthquakes," said Peter Davis, of New York's urban search and rescue task force. "So you just keep looking and keep trying."

Howard Sander, a neurologist at Cornell University, hoped his expertise would be called on to help survivors. So far, apart from hauling buckets, he has been treating rescue workers for anything from smoke inhalation to a sprained ankle. "I don't think we will find any other survivors. It is days without food or water in extremes of heat and nowhere to get clean air. The fire would have snuffed out the oxygen," he said.

Although there is less chaos and desperation than in the first few days of the rescue mission, a mood of deep sadness still hangs heavily over southern Manhattan. The missing include at least 300 firefighters. "It is slow ... so slow," said one fireman, a lieutenant, as he came off a 12-hour shift in the early hours of Monday, physically and mentally exhausted.

Some of those missing were close friends but the lieutenant was trying to block all that out. "The less I think about it, the better I am. I won't think about that at the moment, it's too hard. There'll be time later," he said.

Back at one of the small neighbourhood fire stations, a group of exhausted firefighters talked about their experiences. The station had lost eight, maybe nine officers. No one wanted to put a figure on it, they didn't want to dash any last hope that someone might have survived. Five firefighters were slumped on their chairs. They reflected the ethnic mix of the city: three whites, one Hispanic, one black. They had all just spent 11 hours at ground zero.

Andy Wilson, 23, said: "Please don't call us heroes. I know the media have been doing that. It's a nice thing to say, but it ain't true. We are nothing special, you all would have done the same thing.''

Luis Goncalves, 28, wiping away dirt from his forehead, said: "You don't know these things until it happens to you. What I've realised, man, is how wonderful people are.

"I look at these volunteers and I feel pride. A lot of the stuff we are doing is for ourselves, for our buddies who are trapped down there. Hey, we're getting paid for this.''

He hesitated, before adding: "The worst thing is we have no one to talk to. We don't really talk to each other because we are all supposed to be big macho men. I certainly don't speak to my girlfriend, she worries enough.

"But we have seen some terrible things. We have seen bits of bodies; I saw a woman's hand sticking out, still clutching her handbag. I will never forget the smell of burning flesh. I can't eat anything at the moment," he said.

Mr Goncalves added: "We all got there on Tuesday to discover that some of our pals were already dead. I just don't think about it ­ if I do, I will not be able to do my work."

Asked about the reaction to last week's events, Mr Goncalves continued: "We have got to be careful. I heard one of my neighbours say that he was going to boycott this store because it was run by an Arab. That is stupid, the guy is second-generation here. We are a nation of immigrants."