Two firefighting helicopters have collided while battling a wildfire west of Athens in Greece. The Greek fire service says each helicopter was carrying a two-person crew, and a search-and-rescue operation is now underway.Greece is battling wildfires on multiple fronts, with the Prime Minister warning of “extremely difficult” days ahead. Dozens of homes have been damaged or destroyed, and three firefighters have died this week. Catherine Viette has more.