(Updated 1 p.m.) The Sawmill Fire burning southeast of Tucson has grown to 40,000 acres, officials said Wednesday afternoon.

The new acreage figure showed a nearly doubling in size of the fire from Tuesday night. Hundreds of home remain under pre-evacuation orders, officials said.

Also, Arizona 83 in the fire area remains closed to public traffic, but the closure area has been reduced. The highway is now closed from about five miles north of Sonoita to about 11 miles south of Interstate 10, according to an email from the Arizona Department of Transportation. The original closure was about three miles south of I-10, ADOT said.

Meanwhile a newspaper reported the fire was started by a target shooter.

Several anonymous sources told the Green Valley News that a man was firing at explosive targets on state land Sunday morning, when brush ignited near Box Canyon and the Santa Rita Ranch, according to the article.

The man tried to extinguish the blaze before calling to report the fire to authorities. He later turned himself in, the article says.

Deputy Cody Gress, a spokesman for the Pima County Sheriff's Department, said Wednesday morning that the investigation had been turned over to the U.S. Forest Service, but declined to comment as to if anyone came forward in connection with the fire.

A spokesman for the forest service was not immediately available for comment.

While the fire has grown, calmer winds overnight allowed crews to complete structure protection efforts in the communities of Hilton Ranch and Mescal/J-6 neighborhoods. Crews are also prioritizing structure protection efforts in Rain Valley and the Empire Ranch area, officials said.

The Cochise County Sheriff's Office said the fire is about 12 miles from homes in the J-6 area and residents are still under a pre-evacuation order. The office said a "demarcation line" has been set about six miles southwest of J-6 and if the fire reaches that line, residents will be ordered out of their homes immediately.

Fire crews will also likely begin using air tankers today. The planes were grounded Tuesday because of high winds, officials said.

Evacuation orders have been lifted for the communities of Greaterville and Singing Valley. Residents from those areas will be allowed through the Arizona 83 closure for the sole purpose of checking on their homes.

It was 7 percent contained Tuesday night as a multi-agency crew of 360 battled the wildfire, which a Cochise County sheriffโ€™s spokeswoman described as 10 miles from Benson.

There were no reports of injuries and no structures had burned so far, but homes, ranches and outbuildings, communications facilities and power lines remained at risk, authorities said.

Shortly after 9:30 Wednesday morning, residents of the Rain Valley area were ordered to evacuate their homes, with "dangerous conditions expected," according to a Tweet from the Pima County Office of Emergency Management.

The Southern Arizona Chapter of the American Red Cross has opened two shelters in response to the fire, one located in Sonoita and the other at the Southeast Regional Shooting Park.

The Red Cross moved the shelter in Sonoita Wednesday afternoon to Sonoita Bible Church, 3174 Hwy 83, after the Type 1ย Incident Management Team arrived and set up operations at the Santa Cruz County Fairgrounds.

The higher level team willย assume command of the fire on Thursday, officials said.

Residents of Hilton Ranch were allowed to remain on their properties Wednesday morning, but were advised that evacuation may be necessary if conditions change.

The fire started Sunday south of Green Valley near Madera Canyon and blew northeastward across the northern foothills of the Santa Rita Mountains.

It crossed Arizona 83 in two locations Monday night. That highway, which connects Interstate 10 to Sonoita, remains closed. Forest roads and trails in the area are also closed temporarily.


Become a #ThisIsTucson member! Your contribution helps our team bring you stories that keep you connected to the community. Become a member today.

Contact reporter Caitlin Schmidt at cschmidt@tucson.com or 573-4191