A Kurdish militant group has claimed responsibility for the bombings that killed at least 38 people and wounded more than 150 others in the Turkish city of Istanbul..
The claim was made Sunday by the Kurdistan Freedom Falcons, or TAK, a group seen as an offshoot of the outlawed PKK.
The blasts rocked a huge football stadium late Saturday. Witnesses and authorities said the attacks — a car bombing and a suicide blast — targeted security officers two hours after a football (soccer) match ended.
Turkish Interior Minister Suleyman Soylu said 30 police officers were among those killed.
In pictures: Bombs target Turkish policeView full gallery
Authorities say the blasts targeted a bus carrying riot police from the Besiktas Vodafone Arena on the shore of the Bosporus.
Deputy Prime Minister Numan Kurtulmus said initially that that the outlawed PKK was likely at fault and that said 13 people have been arrested so far in connection with the bombings.
National day of mourning
Turkish President Recep Tayyip Erdogan, who has postponed a trip to Kazakhstan, said in a statement the attack targeted police and "aimed to maximize casualties" and declared a national day of mourning.
The presidential statement described the bombings as an act of terrorism, and said "as a result of these attacks unfortunately we have martyrs and wounded."
Prime Minister Binali Yildirim has ordered flags to be flown at half-staff.
U.S. National Security Council spokesman Ned Price said in a statement, "The United States condemns in the strongest terms the terrorist attack," which he said "appears to have targeted police forces."
The United Nations also issued a statement, saying Secretary-General Ban Ki-moon "hopes that the perpetrators of this terrorist act will be swiftly identified and brought to justice."
Turkey's most visible militant group, the PKK, has for decades battled the Turkish government for an autonomous homeland in Turkey's southeast.
The PKK is widely known for periodic attacks on Turkish security forces. But unlike the Islamic State group, which routinely targets civilians, the Kurdish militants are equally known for avoiding attacks on Turkey's civilian population.
Istanbul has been the scene of several bombings this year, including a June attack at Atatürk Airport that killed more than 40 people. More than 200 people have died this year throughout the country in attacks blamed on Islamic State militants and Kurdish factions inside Turkey.
Islamic State was also blamed for an August 20 bombing at a wedding party in the south-central Turkish city of Gaziantep, near the Syrian border. More than 50 people were killed in that attack and scores of others were wounded.