if you find that no one is in then do not enter unless you have received permission. if you are asked to go away turn back. that is proper for you. god is aware of what you do.
فإن لم تجدوا فيها أحدا فلا تدخلوها حتى يؤذن لكم وإن قيل لكم ارجعوا فارجعوا هو أزكى لكم والله بما تعملون عليم