Residents of the zone in northwestern Iran hit by powerful twin earthquakes described moments of terror and panic with birds crowing loudly in warning seconds before the ground shook.

As the death toll rose Sunday to more than 250 with entire villages leveled, rescuers called off searches for survivors and turned their attention to caring for the 16,000 people left homeless.

At least 20 villages were totally destroyed in the quakes on Saturday that were followed by some 36 aftershocks, state television reported. Ahmad Reza Shajiei, a senior government official in charge of rescue operations, said more than 5,000 tents have been set up to shelter the thousands of displaced who spent the night outdoors.

"The moment the earthquake hit, it was like a snake biting from underground. It was the worst experience of my life," said resident Morteza Javid, 47, from Ahar.

"The walls were shaking and moving from side to side. It took about a minute before I could run out of the house," he said.

"Seconds before the earthquake, crows were making a lot of noise, but I didn't understand why. It was only after the quake that I learned the crows were warning us." Javid said he drove more than a dozen injured people to hospitals during the night.

State television said at least 250 died. The semiofficial Mehr news agency quoted a local official who put the toll at 277. State TV said 44,000 food packages and thousands of blankets have been distributed in the stricken area.

In Washington, the White House press secretary sent a message of sympathy for the victims.

"Our thoughts are with the families of those who were lost, and we wish the wounded a speedy recovery," it said." We stand ready to offer assistance in this difficult time."

The U.S. and Iran are locked in a bitter fight over Tehran's disputed nuclear program, which the West suspect is aimed at producing weapons. Iran denies the allegation.

The UN also issued a message of sympathy and offered aid.

"The United Nations stands ready to lend its assistance," said a spokeperson on Sunday, adding that secretary-general Ban Ki-moon is "deeply saddened" by the loss of life.

"He extends his sincere condolences to the Iranian government and people," said the spokesperson.

Quakes 11 minutes apart

The U.S. Geological Survey reported that Saturday's first quake was magnitude 6.4 and struck 60 kilometres northeast of the city of Tabriz at a depth of 9.9 kilometers. State TV quoted local Crisis Committee chief Khalil Saei as saying the epicenter was a region between the towns of Ahar and Haris, about 600 kilometres northwest of the capital Tehran.

'The walls were shaking and moving from side to side. It took about a minute before I could run out of the house.'—Morteza Javid

The second quake was a magnitude 6.3 and struck 11 minutes later, the USGS reported. Its epicenter was 50 kilometres northeast of Tabriz at a depth of 9.8 kilometres.

The quakes hit the towns of Ahar, Haris and Varzaqan in East Azerbaijan province, state television reported. In addition to 20 villages destroyed, more than 130 others sustained heavy damage, state TV said.

The aftershocks were felt in a wide region near the Caspian Sea, causing panic among the people. Iran is located on seismic fault lines and is prone to earthquakes.

It experiences at least one earthquake every day on average, although most are so small they go unnoticed. In 2003, some 26,000 people were killed by a magnitude 6.6 quake that flattened the historic southeastern city of Bam.

Television showed images of people being evacuated on stretchers, while others were treated for broken limbs and concussions. Dozens of families were sleeping on blankets laid out on the ground in parks. Some were crying, and others shivered from the cold in the mountainous region hit by the quake, near the border with Azerbaijan.

More than 1,100 rescuers worked through the night to pull out those trapped under rubble and to reach some of the more remote villages affected. Some 15 dogs were brought in to search for survivors.

By afternoon, state television reported that search operations had ceased. The government's attention shifted to providing shelter to the homeless and removing debris from the buildings destroyed.

2 days of mourning

Officials said the search was ended relatively quickly because the remote area is sparsely populated.

Naimeh Alapour said she ran out of her house without the mandatory Islamic headscarf when she felt the earthquake. Alapour, 35, lives in Tabriz, the provincial capital, about 50 kilometre from the epicenter of the earthquake.

"I simply took my kid and ran down the steps. The elevator was out of service. I don't know how I walked nine floors down. It felt like this was the end of the world," she said.

Officials have announced two days of mourning in East Azerbaijan province.

Interior Minister Mostafa Mohammad Najjar said the government will allocate funds to rebuild the houses destroyed in the quake, aiming to complete the construction before the arrival of cold winter temperatures.

Najjar said the plans aim to construct buildings resistant to earthquake. Most of houses in rural areas are built of mud, and they can crumble when even a moderate quake hits.

According to Najjar, several foreign countries have offered assistance, but he said Iran doesn't need outside help and can manage the situation. He did not name the countries.

With files from CBC News