[nmader]

You do have a /call command, from there it is likely to be continued under OnPlayerText. Search for "== 911" or something similiar. Also, there is a good sound for a fire alarm for a fire station already in SA:MP. 3401. By using a sound in SAMP it suits the environment better and also doesn't post a message. You would still loop through the player's positions and check if they were in the range of said point.

Hello Patrick. It is I - Nate.