The event occurred on the MMU 002 in the 4A N Mains. The continuous miner was not operating at the time & was positioned in the right barrier lift in the #5 entry in by spad #4227. The CM & the mobile roof support operator stated they heard rock falling in the gob in by the pillar line. When they turned, they saw a flash & were knocked down by a sudden inrush of air & dust.