Various technologies described herein pertain to sharing of detection of active emergency vehicles within an autonomous vehicle fleet. Information specifying detection of an active emergency vehicle at a first location in an environment is received. The active emergency vehicle is detected based upon sensor inputs of a first autonomous vehicle in an autonomous vehicle fleet. A second autonomous vehicle, at a second location, in the autonomous vehicle fleet is identified as being approached by the active emergency vehicle based on the information specifying the detection of the active emergency vehicle at the first location and the second location of the second autonomous vehicle. A remote assistance session for the second autonomous vehicle is caused to be initiated based on the second autonomous vehicle being identified as being approached by the active emergency vehicle. The second autonomous vehicle is controllable by a remote operator during the remote assistance session.