I thought that this subject Emergency Services Trains was a whiff until I Googled each one individually.
Yes there has been ambulance trains, carriages fitted with stretchers used during the Great War. Bachman has a World War I 00 gauge train pack but hasn't bothered detailing the interior carriages with stretchers.
There are Prison trains, which are used to transport prisoners. The carriages converted into individual cells, I haven't been able to find a collectors train set but there's several children's based train sets available. Even a few locomotives painted to promote the Police service.
Then there's Fire fighter trains, either to suppress a fire in a tunnel or trackside. Again geared towards children when it comes to train sets even Thomas the Tank engine and friends getting in on the act.
With plenty of rolling stock in 00 gauge and helicopters small enough to fit on a flatbed wagon, all that is stopping you is your imagination.