ISTANBUL (AP) -- Police on Thursday conducted simultaneous raids on 16 locations in Istanbul, rounding up 13 people suspected of involvement in a devastating attack at Istanbul's Ataturk Airport in which the Islamic State group is the prime suspect.
A senior official said three foreigners were among the suspects detained, but did not provide any information on their nationalities. The official spoke on condition of anonymity in line with government regulations.
Earlier, the state-run Anadolu Agency said the raids were carried out in Istanbul's Pendik, Basaksehir and Sultanbeyli neighborhoods, which span the city's Asian and European sides.
Authorities say all information suggests the shooting and suicide bombing attack by three assailants late Tuesday on one of the world's busiest airports was the work of the IS group.
The official said "extensive soft-tissue" damage had complicated efforts to identify the attackers. "A medical team is working around the clock to conclude the identification process," he told journalists.
The attack killed 42 people, including 13 foreign nationals of whom three were dual nationals. More than 230 people were hurt in the attack. Thursday marked a second day of funerals and mourning.
There was no immediate claim of responsibility by the militant group, which used Turkey as a crossing point to establish itself in neighboring Syria and Iraq. IS this week boasted to have cells in Turkey, among other countries.
In separate large-scale police operations, nine suspects believed to be linked to the IS group were also detained in the coastal city of Izmir. It was not clear if the suspects had any links to the carnage at the airport.
The Izmir raids unfolded simultaneously in the neighborhoods of Konak, Bucak, Karabaglar and Bornova neighborhoods, according to Anadolu Agency. Police seized three hunting rifles and documents relating to IS.
The report said the suspects were in contact with IS militants in Syria and were engaged in "activities that were in line with the organization's aims and interests," including providing financial sources, recruits and logistical support.
Days before the Istanbul attack, on June 25, security forces killed two suspected Islamic State militants who were trying to cross the border illegally and ignored orders from security forces to stop, according to local media reports.
One of the two militants was wanted by Turkey on suspicion that he would carry out suicide attacks in the capital Ankara or in the southern city of Adana, Anadolu said.
Turkey shares long, porous borders with both Syria and Iraq, where IS controls large pockets of territory. The government has blamed IS for several major bombings over the past year, including in the capital Ankara, and on tourists in Istanbul.