Turkish security forces are hunting two attackers after shots were fired at a police station in Istanbul.No casualties have been reported so far.The early morning attack was on Kirac Police Station in the Esenyurt district of Istanbul's European side.After opening fire, the assailants escaped. Police have launched an investigation and increased security at the station.On August 10, a double gun-and-bomb attack on a police station in the Sultanbeyli district of western Istanbul claimed the life of one police officer and wounded at least 10 other people.The Kurdistan Workers' Party, or PKK, claimed responsibility for the suicide bombing and subsequent gun attack.PKK is listed as a terrorist group by Turkey, the U.S. and the European Union.