Police in St. Catharines spent over two hours today negotiating with a man who had locked himself inside a house with what was believed to be a gun.Police were called to Scott Street at about 11:00 a.m. after reports that two men were fighting. One was said to have a handgun.The street was closed between Gineva and Vine Street while police spoke with the man.Officers eventually brought the situation under control and arrested the man. Nobody was injured.Police have not yet announced any charges.