A drunken man in central European Russia`s Voronezh Region threw a grenade on Sunday to the yard of his neighbors who he was in conflict with, injuring four people, police said. "A man, born in 1948, threw a grenade, presumably an RGD-5, to a neighbors` yard where four young people were fixing a car," a police spokesman said. "All four were taken to a hospital. They mainly have fragmentation wounds of legs," he said. The man has so far failed to explain to police where he obtained the grenade. An investigation is underway.