A percussion bomb - a device designed to make a loud noise but cause minimal damage - went off Friday in a courthouse in the Turkish capital, state-run media reported. There were no casualties. The device exploded on the fourth floor of a courthouse in Ankara, where the prosecutors' offices are located, the Anatolia news agency said. Only a few people were in the courthouse at the time of the explosion because the judicial institutions are on a summer recess. There was no immediate responsibility claim. Bomb attacks are common in Turkey, where militant leftists and Islamist groups are active.