NIEGHBOR TO SWAT TEAM: "Hey, what are you guys up to over there?"
SWAT TEAM: "Get him!!"
As I understand the law (and please correct me if I'm wrong), the only time the police are allowed to enter a residence without permission of the owner or a warrant is if a person's life is in danger (ie. hearing someone screaming, followed by a gunshot). But even then, they are only allowed to enter and secure the situation. Any searches have to wait for a warrant to arrive.
If it were a South Park or Simpsons episode, it would be funny.