While they were cleaning, volatile fumes filled the room they were in, and a tiny spark ignited the fumes, which caused an explosion, killing the two men and starting a raging fire in the library.
They were cleaning. Volatile fumes filled the room. A tiny spark ignited the fumes. They were in the room. The fumes caused an explosion. The fumes were killing the two men. The fumes were starting a raging fire in the library.