I have two firex smoke and carbon dectectors, and 3 smoke detectors in bedrooms.

This vlog contains useful information for those dwellings that have the older FireX Smoke Alarms: http://kiddefirex.blogspot.com/

Do they beep three times, pause then beep three times again? if so, they are going into alarm. since they all ring together, the only way to tell which one is causing the problem is to look for one where the leds are different than the others. If your detectors are more than 10 years old, replace them all as required by the national fire code (NFPA72). If they are only doing single chirps, that is usually an indication of a low battery...perhaps the breaker for the circuit has tripped causing them to run on battery only. good luck