An explosion near a sidewalk cafe in an Istanbul suburb injured some 30 people Sunday, police said. The cause of the explosion in the Bakirkoy district was unknown, but police said they suspected a percussion grenade. The Anatolia news agency reported that the explosion occurred in a trash container. One of the injured was in serious condition, Anatolia said. Istanbul's chief of police was investigating the blast site and the injured were taken to a nearby hospital, it said. Kurdish militants recently have planted bombs in Istanbul and threatened more attacks after widespread recent rioting in Turkey's Kurdish-populated southeast.