Roomers are people who rent out rooms. Roomers sounds like "rumors". Rumors are stories of doubtful truth that circulate. "A lot of roomers were flying" can be taken in the literal sense, as in the people renting the rooms were launched into the air. But, it also sounds like "a lot of rumors were flying" which means a lot of stories of doubtful truth were going around.
When a college dormitory exploded a lot of roomers were flying .