EL CERRITO -- An alert citizen and a loud alarm combined to lead police to three juveniles suspected of attempting to burglarize a home on Sonoma Avenue on Thursday morning.

The alarm rang about 8:54 a.m. in the 2600 block of Sonoma Avenue, just as a citizen called police to report the youths possibly casing homes near Charles Avenue and Ellerhorst Avenue, about two blocks away.

Police arrived and found the back door of the home with the alarm kicked in, but it appeared the burglars had been scared away by the alarm.

A detective searching the area detained a suspect near Hazel Avenue and Carquinez Avenue, about eight blocks away from the Sonoma Avenue home. While interviewing the suspect, the detective heard noises in the backyard of a nearby home.

Officers searching the backyard of that home found two more suspects, one of whom was carrying a loaded gun.

All three suspects were booked on suspicion of burglary, conspiracy and prowling and taken to Contra Costa Juvenile Hall in Martinez. The suspect found with a gun was also booked for possession of a loaded firearm. The youths' ages were not released.

Contact Daniel M. Jimenez at 510-262-2728. Follow him at Twitter.com/DMJreports.