A small World War II-era bomb was planted Monday at the door of a German holiday home on the Baltic island of Usedom, police reported. The owner of the house found the explosive device attached by a wire to the door handle and informed the police. Bomb retrieval experts identified it as a German-manufactured bomb weighing one kilogram, fitted with a fuse. The device, filled with 100 grams of explosive material, was still live. ''We have to assume that the bomb would have exploded if anybody had pressed the door handle, causing it to fall down,'' said police spokeswoman Madeleine Camin. Police were investigating the case and considering filing charges of attempted murder. Who was behind the attempted attack, and why, were not known.