Two workmen from the Department of Water and Power were injured when there was a giant short between power cables they were working on in an underground vault at Eighth and Grand Streets, said department spokesman Ed Freudenberg. Both men were taken to Los Angeles County-USC Medical Center, but one of them, who suffered only minor flash burns, was later released. The other man was admitted in serious condition. Neither of the men was identified because their families had not been notified, Freudenberg said. The short briefly interrupted the electricity supply to three nearby buildings, the First Interstate Bank, Broadway Plaza and Fairmont Indemnity Insurance Building.