BAM, Iran (AP) -- Help from the United States and around the world poured into Iran on Sunday, two days after an earthquake reduced most of this ancient city to rubble and killed more than 20,000 people.
Four U.S. planes were among the dozens of foreign aircraft to arrive with aid and workers to assist the stricken people of Bam, where rescuers still rushed to find survivors. There were reports of looting as hungry people raided shops for food and other supplies.
The Interior Ministry estimated the number of injured at 30,000.
Iranian Interior Minister Abdolvahed Mousavi Lari said the death toll from the earthquake in southeastern Iran will exceed 20,000, the first time he gave a specific figure rather than an estimate.
So far, 15,000 bodies have been recovered and buried, Lari said.
"We have not lost hope for survivors and our priority remains to find them," he added.
The leader of an Iranian relief team, Ahmad Najafi, has said he feared the toll could reach 40,000.
The Swiss Disaster Dog Association, the first international search team to arrive in Bam, sent home five trainers and four dogs after deciding there was no chance of finding anyone alive, said Roland Schlachter, head of Switzerland's relief operation.
"The city was 90 percent destroyed, and the people were crushed, suffocated or frozen in the rubble of their mudbrick homes," Schlachter told Swiss radio.
Other volunteers from Switzerland remained to help with reconstruction and other efforts.
Most people in the city of 80,000 were asleep when the earthquake, measured at magnitude 6.6 by the U.S. Geological Survey, struck about 5:30 a.m. Friday. Aftershocks registered as high as magnitude 5.3.
One American was killed and another was injured as they visited the city's 2,000-year-old citadel, a U.S. State Department official said in Washington.
Experts say people buried in the rubble with access to air can survive up to 72 hours, but there have been cases of people living longer.
"We are not quite out of time yet, but time is very short," said Barry Sessions of Britain's Rapid-UK rescue team, which did not find anyone alive in the first 24 hours of its search.
"The earthquake reduced most of (the buildings) to something like talcum powder ... There are few voids or gaps left in the buildings where we would normally find survivors," Sessions said.
The leader of a German rescue team, Gerold Achim, said the reason for the low number of survivors emerging from the rubble was the structure of the houses.
"They collapse into rubble leaving little room for an injured person to survive," Achim said.
Aid workers, many wearing masks against the smell of decaying bodies, arrived from many countries, including Austria, Azerbaijan, Britain, Finland, Germany, Russia and Turkey. Several teams brought dogs trained to detect humans amid the rubble.
The United States said Saturday it would send 75 tons of medical supplies and about 200 rescue and medical experts.
U.S. planes carrying food and other aid landed in Kerman, the provincial capital, early Sunday, said a spokesman for the governor's office, Saeed Iranmanesh. They were the first American aircraft to land in Iran in more than a decade.
The United States has no diplomatic relations with the Islamic republic and last year President Bush included Iran as part of the "axis of evil" with Iraq and North Korea.
"The reception was beyond expectations," said U.S. Air Force Master Sgt. Jeff Bohn, who was on the first American transport plane to reach Kerman. "The warmth that the Iranian military and civil aviation workers gave us was truly incredible."
Forty-five foreign planes have landed in Iran bearing aid, the chief spokesman of Iranian Civil Aviation, Jaafar Poor Sadeghian, told the official Islamic Republic News Agency.
In Vatican City, Pope John Paul II appealed Sunday for a generous and worldwide response to the victims of Iran's earthquake.
People in Bam complained Sunday of a shortage of drinking water. Relief workers distributed bottled water, but there was not enough.
Four men were seen looting three shops in the city center. Two teenagers ran from one store holding packets of biscuits.
Police fired shots in the air to stop another group of looters who broke into a relief warehouse holding blankets and other aid. They also fired into the air to frighten away young men trying to steal motorbikes from a police yard, officer Mahdi Shahsavari said.
Thirty-one temporary police stations were being set up around the city to ensure security, the interior minister said.
Most of the thousands of homeless slept in tents or cars Saturday night, compared with a day earlier when most had only blankets against near-freezing temperatures.
Bam, in southeast Iran about 630 miles from Tehran, suffered such extreme damage because most of the buildings are made of unreinforced mud brick and the quake was centered only about 10 miles outside the city, said Harley Benz, a U.S. Geological Survey seismologist.
The quake destroyed most of Bam's citadel -- a medieval fortress that is the city's best-known structure. The tallest section, including a distinctive square tower, crumbled like a sand castle.
The U.N. cultural agency, UNESCO, considered declaring the citadel a protected World Heritage Site.
Iran has a history of devastating earthquakes, including one of magnitude 7.3 that killed about 50,000 people in northwest Iran in 1990.