Cyprus has declared three days of mourning for the 121 victims of Sunday's crash of a Cypriot passenger jet near Athens. Helios Airways flight 522 slammed into a mountain north of the Greek capital Sunday. The flight originated in Larnaca and was headed to Prague. Authorities say terrorism is unlikely. The Boeing 737 apparently lost cabin pressure or oxygen. The pilot signaled the Athens airport that something was wrong with the plane's air conditioning. The pilot of a Greek military jet flying alongside the stricken plane reports seeing the pilot slumped in his seat and said there was no sign of the co-pilot. One passenger reportedly sent a mobile phone text message to his cousin, saying the cabin was freezing. Investigators have recovered the plane's flight data and cockpit voice recorders.