The revelation came as police raided the home of Ryuji Kimura, the 24-year-old suspect, in Kawanishi, Hyogo Prefecture, in the early hours of Sunday. Police are probing the possibility that the objects used in the Saturday attack on Japanese Prime Minister Fumio Kishida could be homemade pipe bombs, investigators said Sunday, Japan Times reported. The revelation came as police raided the home of Ryuji Kimura, the 24-year-old suspect, in Kawanishi, Hyogo Prefecture, in the early hours of Sunday. Conducting wires found on both ends of one of the cylinders, which resembled a steel pipe, led investigators to believe that the objects may be pipe bombs, as such devices have gunpowder sealed inside a cylinder which is detonated by igniting a fuse, Japan Times wrote quoting NHK. Police are still investigating whether the devices were designed to be lethal. The suspect, Kimura was also carrying a knife in his backpack at the scene, investigative sources said. On Saturday evening, police reportedly urged residents near Kimura's home to evacuate to a nearby community centre as they feared explosives could be found. The neighbours were allowed to return home before dawn on Sunday after authorities confirmed it was safe, Japan Times reported. The searches began at 1 am Sunday (Local Time) and lasted eight hours. Police removed more than a dozen cardboard boxes believed to contain confiscated items in connection with the incident, seizing what appeared to be gunpowder and a computer among other items. Kishida spoke to reporters on Sunday commenting on the incident, calling violent attacks during elections "unforgivable." He added that details on security will be verified as the investigation moves forward and that the nation must ensure safety during the upcoming Group of Seven summit and other events that bring together dignitaries from around the world. "Together with the people of Japan, we will do our utmost to ensure safety during the diplomatic schedule," Kishida said. Kishida was unharmed in the attack, with his security detail taking him to safety shortly before the sound of an explosion rang out and Kimura was subdued. One police officer suffered minor injuries on his left arm, Japan Times reported. During the attack, Kimura reportedly had two cylindrical objects, believed to be pipe bombs about 20 to 30 centimetres long. One object thrown by Kimura landed around a meter from the prime minister as he was about to begin a stump speech for a candidate in a Lower House by-election at Saikazaki fishing port in the city of Wakayama. It exploded a few seconds later, shattering the cylinder. The other was seized by police as Kimura was held down, Japan Times reported. Kimura was arrested on suspicion of obstruction of business and has so far not responded to police questioning, but he has said he will talk once his lawyer arrives, investigative sources have said.