At least 29 people were killed and 166 wounded in a twin blast outside a major soccer stadium in Istanbul on Saturday night.
Turkey's Interior Minister Suleyman Soylu said the bombings inflicted high casualties among police, killing 27 officers, as well as 2 civilians.
Soylu, who rushed from Ankara to Istanbul, had earlier gave an initial wounded toll of 20 police officers.
In a address early Sunday, the minister said 10 people had been arrested in connection with the attacks.
Police cordoned off the area as smoke rose from behind the newly built Vodafone Arena Stadium, known colloquially as Besiktas Stadium after the local team. Witnesses said they also heard gunfire after the explosions.
One of the blasts was thought to be a suicide bomber.
Turkish President Recep Tayyip Erdogan said in a statement, "We have once again witnessed tonight in Istanbul the ugly face of terror which tramples on every value and decency."
The private NTV channel reported that the target of the first attack was a bus for riot police and said nearly 70 wounded were taken to hospitals.
The first and larger explosion took place about 10:30 p.m. after the home team Besiktas beat visitor Bursaspor 2-1 in the Turkish Super League.
The second blast was thought to be a car bomb.
Erdogan said the timing of the attack aimed to maximize the loss of life and vowed the nation would overcome terrorism.
No group has so far claimed the responsibility for the attack.
This year, Istanbul has witnessed bombings attributed by authorities to the Islamic State group or claimed by Kurdish militants. A state of emergency is in force following a failed July 15 coup attempt.
"It is thought to be a car bomb at a point where our special forces police were located, right after the match at the exit where Bursaspor fans" had earlier left, Soylu was quoted as saying by Turkey's state-run Anadolu Agency.
Speaking later to reporters in Istanbul, he said the first explosion took place on a hill adjacent to and overlooking the stadium. The second explosion struck Macka Park and was believed to be a suicide bomb.
Television images showed more than a dozen ambulances on a street hugging the stadium and a police helicopter flying overhead with its searchlights on. The window glass of nearby buildings was shattered by the blasts and coated the pavement. Investigators, including Istanbul Police Chief Mustafa Caliskan, were quickly on the scene.
The Besiktas sports club "strongly condemned" the attack in a statement posted on its website while Bursaspor reported that none of the wounded were fans and issued a statement wishing "a speedy recovery to our wounded citizens."
Aleksander Ceferin, president of European soccer's governing body UEFA, and European Union Enlargement Commissioner Johannes Hahn, also made statements condemning the attack.
"Violence has no place in a democratic society," Hahn wrote on Twitter.
The U.S. Consulate General in Istanbul, meanwhile, urged its citizens to avoid the area which is also home to a Ritz Carlton hotel.
Turkey's radio and television board issued a temporary coverage ban citing national security concerns. It said "to avoid broadcasts that can result in public fear, panic or chaos, or that will serve the aims of terrorist organizations."
(With AP inputs)
