You've got it backwards. The wife came out after 3 hours (late Sunday/early Monday). The police officer was shot after 18 hours (Sunday):
The standoff began about 10 p.m. Sunday when officers from the Hesperia Police Department and the Newaygo County Sheriff's Department had tried to serve the suspect a felony warrant for criminal sexual conduct.
The suspect ran into his home and took his wife hostage, police said. The suspect barricaded himself in his home. About three hours later, his wife escaped the home unharmed, leaving the suspect alone in the home.
Police officers worked all day Monday trying to persuade the man to surrender before the special team entered the home about 4 p.m. and the shoot-out began, McGreevy said. He fired two shots at the officers before the Emergency Support Team entered the home.
http://www.freerepublic.com/focus/f-backroom/942200/posts?page=18#18
Perhaps my language was imprecise. I meant the timing of the article (before the fire), not when the wife left.