Mascher said only those who can show proof of residency would be allowed past a checkpoint.
Evacuation orders for Yarnell remained in place.
The Yarnell Hill Fire was sparked by lightning on June 28. Two days later, violent winds fed the fire and took the Granite Mountain Hotshots by surprise, killing 19 members of the elite crew.
The fire has burned more than 100 structures on about 13 square miles.
Meanwhile, a coroner's office says 19 elite firefighters killed over the weekend died from burns and inhalation problems.
The Maricopa County Medical Examiner's Office in Phoenix issued the finding Thursday, two days after performing the autopsies.
The firefighters had deployed Sunday to what was thought to be a manageable lightning-caused forest fire near the small town of Yarnell.
Violent winds turned the fire, taking the crew by surprise and killing the Hotshot team.
An investigation is underway to find out what went wrong.
The firefighters' bodies will be taken back to Prescott on Sunday.
Fire investigators from across the country arrived on the scene Tuesday night and are expected to spend the next two to three months carefully reconstructing everything leading up to the deaths. Among the many things the team will examine are the radio traffic logs, weather conditions, equipment, the terrain and decisions made by the crews on the ground and incident commanders.
"Our goal is to figure out what happened and make sure it doesn't happen to other firefighters," said James R. Karels, the director of the Florida Forest Service, who is leading the team.
The New York Times