When seconds count, the police are but minutes / hours away..
RE:
The role of the police: Secure the Scene, deploy crime scene tape, mark locations of bodies, collect evidence. Don’t expect the police to protect you under any circumstances.
And:
Per a Supreme Court ruling, 2005, the police are under no legal obligation to defend you, your life, nor your property.
In most jurisdictions, they will do their utmost to prosecute you through the criminal justice system if you live.
When seconds count, the police are but minutes / hours away.That goes for the fire departments, too.
A couple of weeks ago, a thunderstorm cause a large tree branch to fall on our neighbor's garage. It crushed half to the roof and snapped a live power line. The current arced through the house and started a fire.
Even though we witnessed the incident and quickly called 911, by the time the fire department arrived (at least 10 minutes later) the house was fully engaged. This despite the fact the firehouse is less than 3 miles away.
In most circumstances, when an emergency arises, you're on your own.
Many individual policemen will risk their own life to protect citizens and eliminate the criminals, but the institution will almost always do whatever they can do to constrain the actions of the police. The system is built to add to the legal queue, not stop or eliminate crime.