The Altadena Sheriff's Station says that there has been a recent rise in "distraction" burglaries -- where a pair of crooks convinces a resident to let them have access to their house (claiming to have a legitimate reason). Once inside the home, one crook distracts the resident while their partner steals things undetected.
The sheriffs advise that you not allow anyone in your home if you are not sure they are legitimate. If you have doubts, call the company or utility they claim to represent.
If you see any suspicious behavior, call the Altadena Sheriff's Station at 626-798-1131. For emergencies call 911.