This is the hardest opening so far. Officers shooting at you from both sides.
Get them quickly and prepare for more.

The Gold Key is in a secret area in the southern part of the floor.
You don't have to enter the central or eastern parts to get the Silver Key,
but you will be able to locate it from these areas.
Move around back and into the northern part, and through the gold key door.
The Silver Key is behind a pushwall, a 1-up is behind two others.

Then it's the elevator.