ISTANBUL -- Turkey declared a national day of mourning, launched a full investigation and began to bury its dead Sunday after twin blasts in Istanbul killed 38 people and wounded 155 others near a soccer stadium.
The twin car-and-suicide bombings Saturday night near the Besiktas stadium enraged top officials, including President Recep Tayyip Erdogan, who vowed to hunt down the perpetrators. The attack was the latest large-scale assault to traumatize a nation confronting an array of security threats.
The attack targeted police officers, killing 30 of them along with seven civilians and an unidentified person, Turkish Interior Minister Suleyman Soylu told reporters Sunday. He said 13 people had been arrested in connection with the "terrorist attack" and that authorities had some insight into how and when it was planned.
There was no immediate claim of responsibility for the attack but three senior officials said suspicions focused on Kurdish militants.
Deputy Prime Minister Numan Kurtulmus told the private news channel CNN Turk that "arrows point to the PKK," the outlawed Kurdistan Workers' Party, which has waged a decades-long insurgency. That assessment was echoed by Erdogan and Soylu.
Erdogan vowed his country would fight "the curse of terrorism till the end" after paying a visit to some of the wounded at Haseki Hospital in Istanbul.
Surrounded by a crowd of people chanting his name and "God is greatest," Erdogan vowed that the perpetrators would not get away and would be forced to "pay an even heavier price."
The first and larger explosion took place about 10:30 p.m. Saturday after the home team Besiktas beat visitor Bursaspor 2-1 in the Turkish Super League. Erdogan said the timing of the attack aimed to maximize the loss of life.
Soylu said the first explosion was caused by a passing vehicle that detonated in an area where police special forces were located at the stadium exit. A riot police bus appears to have been the target.
Moment later, a person who had been stopped in nearby Macka Park committed suicide by triggering explosives, according to the minister.
Soylu said 136 people remained hospitalized on Sunday after the attack, including 14 under intensive care.
Forensic experts in white uniforms worked overnight, scouring the vicinity of the stadium and the vast park where the suicide bombing took place. Glass from the blown-out windows of nearby buildings littered the pavement.
Authorities have determined that up to 400 kilograms (880 pounds) of explosives were used in the attack, Kurtulmus told CNN Turk.
Vehicle and pedestrian traffic tentatively resumed Sunday in the blast area, which municipal workers rushed to clean up.
At noon, to the mournful sound of trumpets, funeral services were held at Istanbul's police headquarters for some of the slain police officers with the country's top brass in attendance. Their comrades solemnly carried the coffins, which were draped in the Turkish flag, as mourners wept.