Rescue efforts are under way in Iraq and Iran after a 7.3 magnitude earthquake struck the border region between the two countries, killing more than 450 people and injuring an estimated 7,400.

As aftershocks continued on Monday and as rescuers scrambled to find survivors, Tasnim news agency reported that the death toll in Iran has reached 445, while 7,100 have been injured.

In the Iraqi side of the border, Rudaw news website reported at least seven dead and more than 300 injured in the Kurdish region.

The US Geological Survey (USGS) said Sunday's powerful quake hit close to Halabjah, southeast of Sulaimaniyah, a city in the semi-autonomous Kurdish region of northern Iraq.

Iranian President Hassan Rouhani has sent a group of ministers, headed by Interior Minister Rahmani Fazli, to areas impacted by the earthquake to "consider the process of relief" and to "address the injured", according to the Iranian government.

A three-day mourning period has been declared in the province following the disaster.

Tasnim quoted Hooshang Bazvand, governor of Kermanshah, as saying that he expects the death toll to rise.

Most of the victims are believed to be in the Iranian town of Sarpol-e Zahab. An estimated 70,000 people have been displaced across the country.

Al Jazeera's Imran Khan, reporting from the Iraqi capital, Baghdad, said: "The Iranians have moved on the emergency response teams very quickly, setting up field hospitals and moving in heavy machinery to try and get to people that could still be trapped in the rubble."

Across the border in Iraq, Prime Minister Haider al-Abadi offered reassurance to his citizens over the recovery efforts.

"I have instructed Civil Defense teams and health and aid agencies to do all that they can to provide assistance to our citizens affected by yesterday's earthquake. We will do everything possible to help them. Wishing safety and security for all our people," Abadi said on Twitter.

To assist Iraq, Turkey has sent a search and rescue operation of 20 people, including the head of the Prime Ministry Disaster and Emergency Management Authority, Mehmet Gulluoglu.

The government of Iraqi Kurdistan thanked Turkey and President Recep Tayyip Erdogan for the "prompt assistance and offer of help".

The Kurdish Rudaw news agency tweeted a photo of a Turkish cargo plane landing in the Sulaimaniyah airport in Iraqi Kurdistan.

Turkey and Iraq's Kurdish region have been at odds recently over a referendum on the oil-rich area declaring independence from Iraq.

Meanwhile, aid groups in the region are also responding to the earthquake.

Action Against Hunger, a nonprofit whose website says it "works to save the lives of malnourished children", is sending a team to the epicenter of the quake near Halabjah.

Ralph El Haj, spokesman for the International Committee of the Red Cross & Red Crescent Societies, said the Iranian Red Crescent Society has so far deployed close to 174 rescue rapid response teams, who are providing medical supplies, blankets, tents and other facilities to help the injured or to find those still trapped under the rubble.

"It's important in these situations to also refresh the memories of people on how to deal with earthquakes," he told Al Jazeera on the phone from Baghdad.

Crossed by several major fault lines, Iran is one of the world's most seismically active countries.

In 2003, a 6.6 magnitude earthquake flattened the historic city of Bam in southeastern Iran, killing some 26,000 people.

On the other side of the border, Sulaimaniyah officials declared an emergency in the early hours of Monday to assess the aftermath of the quake, according to local Kurdish media.

Its epicenter was at a depth of 33.9km.

Politicians and social media users have offered their condolences to the neighboring countries.

"Our thoughts and prayers are with the Iranian and Iraqi brothers who lost their lives in this tragic calamity," said Pakistan's Foreign Minister Khwaja Asif.

UK's Labour Party leader Jeremy Corbyn urged "urgent support" for those affected by the quake.

"My thoughts are with the victims of the devastating earthquake which hit Iraq and Iran yesterday," he wrote on Twitter.

Thousands have been left without shelter and many without medical treatment. We must do all we can to provide urgent support."

Those affected by the quake also described the moments of the tremor on social media.

"Woke up to my bed shaking and entire room shaking with the sounds of crumbling in Najaf," one Twitter user said.

Al-Jazeera