Greek police defused a car bomb outside Citibank's headquarters in Athens on Wednesday, hours after gunmen shot at a private television station, dpa reported. Reports said the stolen car was parked in the courtyard of Citibank's offices in the northern Athens suburb of Kifissia. Ani-bomb forces defused the home-made device after a security guard called police after seeing three men leave the vehicle. The incident followed a spate of gun attacks across the city by suspected militant groups against police and journalists since the police shooting of a 15-year-old boy in December. The shooting of the teenager triggered Greece's worst riots in decades. A day earlier, unknown gunmen opened fire at a Greek private television station. No injuries were reported. No group has claimed responsibility for the shooting but officials said the weapons used were similar to those used against a police station. A previously unknown group, Rebels Sect, claimed responsibility for the attack on the police station.