Paradise, a hilly and wooded community in the Sierra Nevada, is connected to the outside world by the main road, called Skyway, and a few other smaller roads. Even without the broader warnings, panicked residents spent hours stuck on Skyway trying to escape to Chico, the city in the valley below, and some died as flames engulfed their cars.

“I understand there are people who say they didn’t get enough notice — I agree,” Sheriff Honea said in an interview this week. “There was not enough notice. We couldn’t have given enough notice given the circumstances.”

Similar questions were raised during the wine country fires in Sonoma County in Northern California last year. The Tubbs Fire was briefly the state’s most destructive wildfire, with more than 5,500 buildings burned. Officials there also decided against sending out a mass alert to every cellphone in the region because they feared it would clog up roads both for evacuees and emergency vehicles. And in the aftermath of deadly mudslides earlier this year in Montecito, which killed 21 people, the authorities were sharply criticized for not issuing mandatory evacuation notices.

In last year’s Tubbs Fire, warnings were sent out to those who subscribed to a police notification system known as Nixle.

“We know from the Tubbs Fire of a year ago that subscription rates are low,” said Thomas Cova, a geography professor at the University of Utah who specializes in emergency management. “They discovered in hindsight that they were reaching very few homes.”

This was a lesson, he said, that was not applied as disaster unfolded in Paradise.

“It’s really disappointing,” he said. “You’d think with what happened in Sonoma County, that other counties in California and elsewhere would review their systems and go door-to-door to get everyone subscribed, or whatever it takes.”