A man in his 30s has been arrested for killing a neighbor with a long sword in Seoul, police said Tuesday.The 37-year-old used the 80-centimeter-long sword to kill the neighbor at the gate of an apartment complex in Seoul's northwestern district of Eunpyeong at around 11:30 p.m. Monday for unclear reasons, police said.The two lived in the same apartment complex but did not know each other well.After the crime, the man fled to his home but was caught one hour later.Police are investigating the exact motive and other circumstances of the crime and plan to seek a formal arrest warrant for him.Source: Yonhap News Agency