Another shooter could have walked into an adjoining room. In fact, another shooter in an adjoining room could have called the front desk to report shooting. Don’t rule anything out except the public will never know the whole truth.
Another shooter could have walked into an adjoining room.
Both broken windows were in the same suite. Schematics have been posted showing the suite with two separate bedrooms and a big common area spanning the corner. Corner suites are big (and expensive).