The Los Angeles Police Department cautioned drivers this week not to use navigation apps like Google Maps and Waze while trying to find their way from a fire zone.
Officials said some drivers attempting to circumvent the Skirball Fire, which shut down the 405 in the Sepulveda Pass, were routed into neighborhoods that were burning and under evacuation orders.
While navigation apps for smart phones can provide a great service in times of emergencies, the data they use don't always reflect the threats on the ground.
Waze Mobile does collaborate with agencies and local jurisdictions, such as the city of Los Angeles, to update routes with information on construction zones and road closures.
But in a fast-moving situation like the fires this week, that data can be limited as well as slow to update on the app.
Representatives from the Los Angeles Department of Transportation said information about road closures filters through several verification checks starting from field officers on the ground before it is reported to Waze. The department doesn't collaborate with Google Maps, but the app pulls some alerts from Waze, which is also owned by Google.
Each navigation app operates by its own proprietary algorithm to calculate the best route. It is based on variables like speed, distance, traffic dynamics and level of preference for main roads over small neighborhood streets.
It's possible in the case of the latest fires that some empty roads in the line of the flames could have appeared as attractive routes to the algorithm, because no data about the borders of the evacuation zone were transmitted to the apps.
Waze is known for prioritizing shorter trips very highly, with lower priority given to keeping to main roads.
Residents in the neighborhoods along the 405 through Sepulveda Pass have complained for years that the Waze app has sent a stream of heavy traffic through their narrow canyon roads, which hamper emergency response even on a good day.
Los Angeles City Councilman Paul Krekorian has even tried to get Waze to remove some smaller streets in the area from its routing, but to no avail.
Waze does allow users to submit warnings about traffic obstructions or dangers, but it doesn't always change the route to avoid the dangerous areas.
Waze and Google officials did not immediately respond to a request for comment.
Officials say the best bet for drivers is to monitor emergency notices and steer clear of the roads and neighborhoods where a disaster is affecting traffic.