I know that. But it isn't the best way to shut the engine down quickly.
To shut down the engine as quickly as possible, you should use the fuel control switch, then pull the fire handle. The fire handle usually shuts the fuel off at the spar valve, way upstream from the engine, whereas the fuel control switch shuts off the fuel valve right at the engine. If you just pulled the fire switch, that engine would run for a while as it burned all the fuel in the line between the spar valve and the engine itself. To shut it down the quickest... use the fuel control switch, then pull the fire switch to shut off the hydraulics, pneumatics, electrical, etc. to that engine.
I don't know about the 737. Never flew it. But this is the Engine Fire, Severe Damage or Separation checkist from a B757. I'm sure the 737 is similar.