Task: Question Answering
Input (English): Context: DENVER We d . August 27th - There were some tense moments at the Unconventional Denver convergence space Wednesday morning when police set up a perimeter around it and attempted to enter and search the building . Security at the space demanded a search warrant when police asked to enter the space . Legal aid was called to the scene immediately where video and written accounts were taken . Police were unable to obtain a warrant and left after some time , but not before arresting 2 activists outside the center . 
Question: What may be the reason the police left ?
Output (English): They did n't have a warrant .