By Nidal al-Mughrabi and Ahmed Shalaby CAIRO, June 11 (Reuters) - Israeli strikes killed three people in the Gaza Strip on Thursday, health officials said, as mediators struggled to make progress in renewed efforts to reinforce a fragile U.S.-brokered truce, sources close to the talks reported. Medics said an Israeli strike on a house in Moghrabi Street in Gaza City killed one person. The Israeli military told Reuters it struck a militant.