Turkish officials said the three suicide attackers who targeted Istanbul Ataturk Airport on Tuesday were from Russia, Uzbekistan and Kyrgyzstan.

Turkish police said they arrested 13 people in connection to the airport gun and bomb attack that left at least 42 dead and hundreds injured.Police, in 16 raids across Istanbul, detained the suspects Thursday. The police department’s anti-terror branch is continuing its search for three other suspects in Turkey’s most populated city. Another nine people were arrested in the coastal city of Izmir, although it is not clear if they are related to the airport attack.Officials have blamed the terror group Islamic State, also known as ISIS, ISIL and Daesh, for the Tuesday attack on the airport that left some 239 injured, but there has been no official confirmation from the group. Prime Minister Binali Yildirim said the investigation is ongoing.