A fire that broke out yesterday at a nightclub in central Athens, where Greek pop singer and teenage heartthrob Sakis Rouvas is currently performing, is being treated as arson, police said. The blaze began at about 7 a.m. and it took some 30 firefighters and 10 fire engines more than an hour to extinguish the flames. The club was closed at the time so there were no injuries but the damage was extensive. The security guard told police that he was hit on the head with the butt of a gun by one of three people that approached him early yesterday. They then tied him up before allegedly setting fire to the S Club on Vouliagmenis Avenue. Police said forensic experts found clues that indicate the nightclub was deliberately torched.