At least 445 people have been killed and around 7,300 are injured after a 7.3-magnitude earthquake hit the border of Iran and Iraq.
The powerful quake, which struck 19 miles outside the eastern Iraqi city of Halabja, was felt as far west as the Mediterranean coast.
Its worst damage appeared to be in Iran's western Kermanshah province, which sits in the Zagros Mountains that divide Iran and Iraq, where residents in the rural area rely mainly on farming to make a living.
Iranian social media and news agencies showed images and videos of people fleeing their homes into the night as some 50 aftershocks followed.
Esmail Najar, head of Iran's National Disaster Management Organisation, said some people might be buried under the rubble.
Iran's state-run television reported the increase in casualties and said rescue work was continuing.
Iran's Supreme Leader Ayatollah Ali Khamenei offered his condolences on Monday morning and urged rescuers and all government agencies to do all they could to help those affected, state media reported.
Iran is prone to quakes as it sits on many major fault lines.
In 2003, a 6.6 magnitude flattened the historic city of Bam, killing 26,000 people.
The last major casualty earthquake in Iran struck in East Azerbaijan province in August 2012, killing more than 300 people.