Pretty simple really, The line of clouds was probably a moisture starved outflow boundary and thus simply the cloud you seen, It was colored by the setting sun. The birds are blackbirds and quite common in mass at that time of the year, Yes literally billions of them. And the guy trashed the lobby and the cops surrounded him and arrested him at the pool. The birds were just heading to settle in trees and thus left the sky.

Not everything is an alien or a conspiracy.