听到 / 防空警报 / 后 / 大家 / 按照 / 指示 / 迅速 / 卧倒 / 并 / 保护 / 头部

听到防空警报后，大家按照指示迅速卧倒并保护头部。

After hearing the air-raid alarm, everyone quickly dropped to the ground and protected their heads as instructed.