Only the delusional and criminally negligent say otherwise.
H/T: Svend Andersen
Sweden Report: Police: Yes, there ARE No-Go Zones in Sweden
The original term is military lingo for hot areas controlled by the enemy, where it is suicidal to venture without sufficient firepower to match that of the enemy. This describes the situation of police officers pretty well; you have to enter the area in force or stay out, since a lone patrol car WILL be attacked.
NOTE: The TT and others in the Counter-jihad visited Malmö/Rosengård Sweden some years ago, and interviewed some of the police changing guard (shifts) in a gas station in Rosengård.