Some security grids are installed with an internal quick release feature just for this purpose. Doors with glass windows should be equipped with a double key dead bolt lock, key operated both inside and out. Buy at least five boxes of ammunition for your house gun. And shoot up four of them in practice. Pick a load with a controlled expansion bullet.
Many departments have and been swamped by interested citizens.
Find out what your state's laws are regarding deadly force and self defense. Talk with a lawyer and consider what he says in defining your intruder response plan. If you know what to do when facing an intruder, you won't appear indecisive and vulnerable. If you have practiced with your gun, you'll look like you know what you're doing. You may not have to fire the gun at all.