KYIV/ZOLOCHIV, Ukraine, March 9 (Reuters) - Russia fired a huge wave of missiles across Ukraine on Thursday as people slept, killing at least nine civilians and knocking out power in an attack Kyiv said included six Kinzhal hypersonic cruise missiles, one of Moscow's most valuable weapons. Ukraine said the attacks had knocked out power in various places including to the Zaporizhzhia nuclear power plant, Europe's largest, severing it from the grid and forcing it onto emergency diesel power to prevent a meltdown. Moscow, which claims to have annexed a fifth of Ukraine, says it launched its "special military operation" a year ago to combat a security threat