(Adds house struck belongs to Hamas militant, details) GAZA, May 20 (Reuters) - An Israeli tank shell struck the home of a Hamas militant in northern Gaza on Sunday, wounding him and four of his children, one of them critically, medics said. An Israeli military spokesman had no immediate comment. Palestinian security and Hamas sources said Israel had fired at the home in Beit Lahiya, an area in northern Gaza from where gunmen launch rockets at Israel, wounding the gunman and injuring his children aged between two and 12. A boy was listed in critical condition, medics said. The shelling occurred shortly after Israel killed eight Palestinians in Gaza City, in one of its worst air strikes in months in the coastal strip. The air raid struck the home of a Hamas lawmaker. The Israeli army said it had aimed at gunmen. Israeli Prime Minister Ehud Olmert said earlier his cabinet had decided to step up assaults in Gaza against militants involved in firing rockets at the Jewish state. About a dozen Israelis have been wounded by rocket fire from Gaza in the past week.