A 20-kilogram bomb went off in Elefsina, west of Athens, early yesterday, damaging 30 buildings and about 20 parked cars in what police believe was an attack related to nightspot protection rackets. One man was slightly injured in the explosion caused by 20 kilos of dynamite at around 4 a.m. outside of the Boss cafeteria, which was completely destroyed in the blast. «The explosion was more like an earthquake. It has damaged shops within a radius of three to four blocks,» one local resident told a Greek radio station yesterday. The targeted coffee shop belongs to the mother of a convicted criminal, currently serving time in prison for murder, protection racketing and other crimes. Initial evidence gathered at the crime scene by bomb experts point to an explosive device containing large amounts of dynamite that went off using a slow burning fuse, said one police source. A similar attack against the same cafeteria had taken place in December 2003 in an explosion that had once again destroyed the store. Six people had been charged in connection the incident after police found traces of the explosive material on their clothes. The man injured from the blast yesterday was an on-duty police officer who had been appointed to guard a woman whose house is located near the area the explosion took place. The police officer, who suffered face injuries, was guarding the woman after she had been placed in a witness protection program for giving evidence against criminal gangs in 2002. The woman had turned to police, testifying against an alleged crime boss after a relationship with him had ended. A security guard employed at the Boss cafe narrowly escaped injury, as he ran from the area once he spotted the explosive device. Police said attacks between protection racketeering gangs appear to be increasing, despite many of the key suspects involved serving time in different prisons. Most of the clubs the gangs are battling to control are in western districts of Athens.