A British Airways Boeing 747-400, registration G-CIVF performing flight BA-268 from LAX to LHR, was enroute at FL330 about 145nm southeast of Las Vegas when the crew donned their oxygen masks and diverted the aircraft to Las Vegas requesting medical assistance to await the aircraft, they had four crew members feeling unwell.
See:
British Airways plane makes emergency landing in Las Vegas - www.ktnv.com