From beneath the rubble of what was Armero, now a mass of broken concrete slabs and twisted corrugated metal, of scattered belongings and crushed bodies buried under brown watery slush, came the cries today of survivors alive two days after a volcanic eruption caused a flood of mud that swallowed this town.

But few were here to save them.

Officials in Bogota, who had declared a national emergency after the eruption Wednesday of Nevado del Ruiz volcano, reported that aid had begun to arrive from the United States, Europe and international agencies. But only a tiny amount of material and a small number of volunteers have arrived so far to this main scene of disaster.

Relief workers, laboring in hot, humid weather amid the rising stench of spoiled food and decomposing bodies, said there was a desperate shortage of supplies and personnel. As they worked, more tremors and rumbles were felt from the volcano.

Government and relief officials estimated that as many as 20,000 people may have died in the disaster and thousands more have been injured. But those on the scene stressed that a complete casualty count would not be possible for a long time.

Walter Cotte of the Red Cross said many of the dead were buried in mass graves without being photographed or fingerprinted. One relief official said it would probably be necessary to declare Armero "holy ground," leaving many of the dead buried where they died. Hastily constructed tent hospitals were set up in the nearby towns of Mariquita, Lerida and Guayabal, civil defense officials said, but there were few helicopters to carry the victims there and no roads were passable in the narrow Andean valleys near Armero. "We don't have the help we need," said Raul Alferez who is in charge of the Red Cross medical unit here. "We need people, we need equipment, but we have next to nothing."

The magnitude of what has to be done is overwhelming. What was once a picturesque country city of 25,000 people is now a mangled mass of junk and corpses.

Traces of ruined lives lay strewn across an area about 80 acres wide, where a raging river of mud and stone swept over this town.

Only a few of the buildings that once made up Armaro's center are still standing.

Over where the coffee warehouse once stood, bags of beans floated on the muddy mess.

One man was scouring the wreckage for whatever could be salvaged -- a television set, some plastic plates, a spool of wire. Wiping the mud off the spool, he tested the strength of the wire and appeared satisfied. Where neat rows of buildings once stood there is now just a sea of mud. A few isolated rooms jutted above the mud.

In one such room -- a three-sided concrete box with the front missing -- several men were sifting through the remains. It used to be an appliance store. A fan, a blender and some spare cords were found.

Scavengers are everywhere. Rodrigo Salcedo, 27, from the neighboring town of Honda spotted an artificial Christmas tree and perched it on his head.

"Those of us who survived have a right to live," he said when asked about his new possession.

Two boys from the town of Guayabal, several miles up the valley from Armero, had stuffed their pockets. One collected dozens of ballpoint pens, a precious commodity in this poor region. The other collector pulled a bottle of perfume and another of deodorant from his jacket pocket, showing off his finds.

Jaime Hernandez, a 22-year-old farmer and Armero resident who survived the avalanche, stood surveying the destruction, chewing on a coconut he had cut open with a foot-long machete.

Food is a serious problem, said Hernandez, explaining how he had scrounged for the coconut. As visitors arrived during the day, children ran up to them, hands extended, begging for something to eat or drink.

In the low hills above the city, several hundred people have camped in makeshift huts with tin roofs. They are the lucky ones, those who managed somehow to escape the waves of hot mud and debris that swept through Armero.

But they were not being evacuated. Relief officials said priority for seats in the nine or 10 helicopters ferrying people to and from the disaster site was given to the injured.

On the northwest side of Armero, several bulldozers were pushing back the mud, trying to open a road into the town. But it could be days before emergency land vehicles can reach here.

The Red Cross has set up a tent and evacuation area in a clearing several hundred yards from where the mud stopped. Only five medics and 15 volunteers made up the Red Cross team today, according to Alferez. Also helping in the rescue effort here were about 10 blue-suited Air Force members and about the same number of orange-suited Civil Defense workers. Yesterday, emergency teams pulled survivors off the roofs and trees where they had climbed to escape the avalanche. Today, the rescuers searched for those buried alive in the mud.

Alferez estimated that 1,000 people could be trapped alive in the city's ruins. An Argentine medic participating in the relief effort, 23-year-old Alejandro Jimenez, guessed that there could be 2,000.

As of early this afternoon, Alferez, who was not keeping exact records, said about 65 injured survivors had been found and flown out today.

But there is no organization, no plan, to search for the living. It is a hit-or-miss operation. Survivors have been located most often when their screams or cries were heard by passers-by.

Once survivors are found, the process of freeing them is a lengthy, arduous effort.

One team of workers spent much of this morning trying to pry a 34-year-old man from his collapsed house while, a few yards away, another team chest-deep in water sought desperately to lift to safety a 13-year-old girl whose feet were pinned by fallen concrete.

The man, Efrain Gomez Primo, a peanut farmer and candy vendor, was stuck under his collapsed house. He talked about his ordeal as rescue workers hacked away with machetes at the boards that imprisoned him.

He said the walls of his house fell in Wednesday night as he was trying to flee the raging current. After the volcanic storm had subsided, he said he started screaming for help. His brother found him at 6:30 yesterday morning and told him not to worry, that the Red Cross, Civil Defense and Army were on their way. The brother never returned.

A Civil Defense worker who arrived soon afterward lacked the necessary tools and left. It was not until late this morning that a rescue squad arrived.

By then, a middle-aged woman, who had been caught in the wreckage with him and was in great pain through last night, had died. Her corpse lay facing up on a sheet of tin.

"I'm half dead," he said, as the effort to free him began. No one had given him anything to eat or drink for more than 36 hours. Gasping for air, he exclaimed, "I can barely breathe."

When he was finally pried loose and carried to the evacuation zone, medics had no splint for Gomez's broken right leg. They tied a strip of cardboard around it.

Just a few yards from Gomez was the girl, Omira Sanchez. She had been found just after dawn yesterday by an Air Force officer working in the rescue campaign. The first problem was how to pry loose the stiff arms of the girl's dead aunt, who had grasped the child the night of the tragedy.

Sanchez said the waters of the ravaging Lagunilla River had prevented her aunt from opening the door of their house. All during that stormy night, before she died, the aunt kept apologizing for not having managed to rush the family to freedom, the niece recalled.

The girl's eyes were bright red and swollen. When rescue workers called for an anesthetic, there was none.

She asked for cookies, but there were none of those either. Somehow the girl managed to stay calm and lucid, closing her eyes in pain at times, breaking into tears at other moments.

She would wrap her hands around the neck of a rescue worker standing in the water in front of her and try, with all her might, to tear herself free of whatever was keeping her feet pinned down. But she could not budge.

Workers dug around her, lifting out huge blocks of broken concrete. Rescuers feared that rising water would drown the girl if they couldn't get her out soon. Her head was just above the water line.

Watching the desperate attempts to save the girl, Alferez, the Red Cross chief, shook his head in despair.

"This makes one feel useless," he said. "What can we do?"

Describing how ill-equipped rescue workers here are, Alferez rattled off a list of urgently needed supplies -- power generators, water pumping machines, medicine, bandages, stretchers, food and drink.

He said the supplies being sent by foreign countries were going to an Air Force base.

"I was there this morning and there was a lot," said the 20-year-old Red Cross volunteer who hopes to study medicine in the United States. Asked why he thought the material hadn't yet reached this primary disaster area, Alferez replied: "Poor communications."

The people of Armero are bitter about the disaster. In interview after interview, residents who survived said the loss of life could have been prevented. They said the government knew the volcano might erupt, and when it did, officials failed to react fast enough to evacuate the town.

When the ashen rain started falling heavily around 6 Wednesday night, many in Armero turned on their radios. They heard Jairo Monroy, the local radio announcer, saying reassuringly that there was no cause for alarm.

So the people of Armero went to sleep.

It was only four hours later that the alarm was sounded. By then, the volcano had exploded, sending broken hunks of melted glacier ice racing down its slopes into the valley below.

But even then the signals that authorities gave were confusing.

Alirio Oliveros, a farmer, said that to warn citizens and wake up the town, police shot their guns in the air at about 10 p.m. Wednesday. Oliveros mistook the shooting for an attempt by the M19 guerrilla group to take over the town. He said that instead of running into the street and to high ground, he and his family "hid even more" in their house, which was subsequently washed away.