The system is used to notify residents in emergency situations . During the 2010 Boston water emergency , government agencies used the system to notify a large number of Boston-area residents in particular neighborhoods to boil water before drinking . During the much more contained 2004 bulldozer rampage in Granby , Colorado , authorities used Reverse 911 to notify the approximately 1,500 residents of the town to evacuate from the bulldozer 's path . During the 2011 Tōhoku earthquake and tsunami , Seaside and Astoria , Oregon , residents were notified by Reverse 911 and sirens to evacuate low-lying areas . When the improvised explosive devices in the Aurora , Colorado , apartment of 2012 Aurora shooting gunman James Holmes were detonated by police , Reverse 911 was used to notify nearby residents of the evacuation order . On December 14 , 2012 , Reverse 911 was used to notify parents in the Sandy Hook community of Newtown , Connecticut , of the Sandy Hook Elementary School shooting incident . During the manhunt for suspects involved in the Boston Marathon bombing , Reverse 911 was used to notify residents of Watertown , Massachusetts , to remain in their homes . In October 2014 , some Dallas , Texas , residents were notified of the city 's second Ebola infection case by a Reverse 911 call
2011 Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
Reverse 9-1-1