Leaders from around the world have issued statements condemning Saturday's terror attack near a football stadium in Istanbul that killed at least 29 people and injured 166 others.
In Washington, the White House condemned the attacks "in the strongest terms", and pledged solidarity with Turkey.
"Our thoughts and prayers go out to the victims, their families and loved ones, and to all the people of Turkey," National Security Council spokesman Ned Price said in a statement.
We stand together with Turkey, our NATO Ally, against all terrorists who threaten Turkey, the United States, and global peace and stability.
On his Twitter account, Canadian Foreign Minister Stephane Dion said Canada strongly condemned the deadly attack in Istanbul.
"Our thoughts are with victims and families and the people of Turkey," Dion said.
The president of the European Parliament posted a comment on social media. "My thoughts & solidarity with Turkish citizens, with families of victims of Istanbul attacks. I wish speedy and full recovery to the injured," Martin Schulz said.
A spokesman for Council of Europe secretary general said Ankara would find support from Europe. "Turkey can rely on the solidarity and support of European governments and the Council of Europe after today's Istanbul terrorist attack," Daniel Holtgen said.
"All our solidarity to all citizens of Turkey," EU High Representative for Foreign Affairs Federica Mogherini posted on her Twitter account.
Read: Terror attack in Istanbul claims 29 lives
NATO Secretary General Jens Stoltenberg condemned the attack, calling it "horrific acts of terror." He stressed that NATO stood united in solidarity with its ally Turkey. "We remain determined to fight terrorism in all its forms," he added.
UK Foreign Secretary Boris Johnson said the "UK [was] committed to working with Turkey to tackle terrorism", adding that his thoughts were with all those affected.
In a statement, UN Secretary General Ban Ki-moon expressed his deepest sympathy and condolences to the families of the victims. "He hopes that the perpetrators of this terrorist act will be swiftly identified and brought to justice," the UN website reads.
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France, Germany, Russia condemn attack
On his Twitter account, French President Francois Hollande denounced the blasts, showing his support to Turkey.
German Foreign Minister Frank-Walter Steinmeier condemned the attack and said Germany was mourning with Turkey.
Hungarian Foreign Ministry spokesman Tamas Menczer said the attack was committed against the European Union as well. "The security of Europe starts with Turkey's stability," he said.
Russian President Vladimir Putin also expressed condolences for those who lost their lives, condemning "this cowardly, cynical crime".
Azerbaijani President Ilham Aliyev decried the attack and urged for "a resolute fight against any kind of terrorism".
Kazakhstan President Nursultan Nazarbayev and Georgian Prime Minister Giorgi Kvirikashvili expressed condolences to the families of the victims and added they were ready to show support in Turkey's fight against the terrorism.
The Malaysian government also strongly condemned the attack, calling it "inhumane" in a statement issued by the country's Foreign Ministry said.
"The Malaysian government expresses its deepest condolences to the government and people of Turkey, as well as to the families and victims affected by the attacks," it added.
Qatar, Kuwait, Afghanistan, Iraq, Israel, Iran, Palestine, Jordan, Bahrain, the United Arab Emirates (UAE) and Tunisia also condemned the attack, showed solidarity with Turkey.
UEFA condemns 'horrible act'
On Twitter, European football's governing body, UEFA, "strongly" condemned "the horrible act" and sent its support to the Turkish Football Federation, Besiktas and Bursaspor football clubs.
UEFA would like to express its deepest condolences to the families of all the victims of tonight's bombing in Istanbul
At around 10.30 p.m. (1930GMT) on Saturday evening, two explosions rocked Istanbul's European side.
Outside a football stadium in Istanbul's Besiktas district, a car bomb was detonated two hours after the end of a Turkish league football match between Besiktas and Bursaspor.
Seconds later, a suicide bomb attack occurred in Macka Park in the same neighborhood. The suicide bomber blew himself up after police noticed him, according to Interior Minister Suleyman Soylu.
"A total of 13 suspects have been arrested so far," he said. "Signs point to the involvement of the PKK terrorist group."
Deputy Prime Minister Numan Kurtulmus also said Sunday that the PKK terror group was "most likely" to have been involved in Saturday's deadly terror attack.
The Turkish Prime Ministry said in a statement, a day of national mourning has been declared on Sunday. The national flags will be flown at half-mast across Turkey and at foreign delegations, it added.
Turkish political leaders stress determination in fight against terrorism