UPDATE, 7:27 p.m.:FLAGSTAFF - The second wildfire to hit this forested city in two days grew to 3,000 acres Sunday, driving residents from hundreds of homes and prompting a search for some missing hikers.Meanwhile, evacuation orders for the first fire, in southeastern Flagstaff, were lifted after fire officials reported it 30 percent contained. Earlier Sunday, a man was arrested on suspicion of causing that fire by dumping coals from a campfire on the ground, city spokeswoman Kimberly Ott said.Authorities announced the news about the hikers and revised the number of evacuations for both wildfires at a Sunday evening press conference. They didn't specify how many hikers were missing but said "two active searches" were under way.Authorities also announced that a third fire was reported near Interstate 40 in western Flagstaff. They said that blaze was caused by a vehicle fire that spread into a wooded area, but there was no word on its size.Ott said residents of hundreds of homes on 1,044 parcels just north of Flagstaff were being advised to leave because of the Shultz fire, which was reported Sunday morning and was spreading quickly.Four helicopters and 300 firefighters were battling the blaze, and more crews were on the way, Ott said. Eight air tankers were ordered but had been grounded because of wind."There's a pretty impressive towering column of smoke," said Coconino National Forest spokeswoman Karen Malis-Clark.The American Red Cross set up a shelter at a Flagstaff middle school for displaced residents.Authorities knew of no buildings that had been burned. U.S. Route 89 northeast of the northern Arizona city of about 60,000 was closed because of smoke from the Shultz fire. Its cause was unknown.Meanwhile, residents of the 116 homes evacuated because of the Hardy fire in southeastern Flagstaff were being allowed to return, Ott said. A California man was arrested on suspicion of starting the fire, which erupted Saturday, by leaving behind hot coals at a campsite in a wooded area about two miles from downtown Flagstaff."As far as we understand, this was not a deliberate act. It was a careless act," Ott said.Randall Wayne Nicholson, 54, was arrested on a misdemeanor charge of burning of a wildland, Ott said. Nicholson, whose hometown was not immediately available, was being held on a $2,500 bond at the Coconino County jail. It was unknown if he had an attorney.The Hardy fire quickly spread up a hill and threatened homes in two neighborhoods. Crews worked overnight and Sunday to protect structures and establish a perimeter around the blaze.Fires also had crews busy Sunday near Williams, Ariz., and in Colorado and New Mexico.High winds and rugged terrain kept ground crews and aircraft from getting close to a wildfire in southern Colorado's Great Sand Dunes National Park. The fire grew to 4,500 acres.In New Mexico, crews were making progress on the South Fork fire, which had charred more than 11,150 acres in steep, inaccessible terrain in the Jemez Mountains.Fire danger is considered high to extreme in Arizona, which has seen two wildfires burn more than 3,000 acres each in the last month."The Southwest had a wet winter and then the spring turned dry," said Rick Ochoa of the National Interagency Fire Center in Idaho. That combination has "increased the fire potential quite a bit in the Southwest," he said.Relief isn't expected until next month, when summer monsoons generally start bringing rain to the region.INITIAL REPORT, 3:17 p.m.:FLAGSTAFF - A thick plume of smoke blotted out the blue sky north of Flagstaff on Sunday afternoon as a second wildfire moved through the area, forcing the evacuation of additional homes and an animal shelter.Coconino County authorities said residents of the Timberline Estates, Wupatki Trails and Fernwood neighborhoods were being asked to leave their homes. Authorities couldn't immediately say how many people were affected.The Second Chance Animal Shelter also was being evacuated.About 170 homes already were evacuated Sunday because of the 350-acre Hardy wildfire on the southeastern side of Flagstaff, which started Saturday.The second blaze was spotted Sunday on the north end of Shultz Pass. Coconino National Forest spokeswoman Karen Malis-Clark said the fire was torching treetops and sending up a "pretty impressive towering column of smoke."Hot shot crews, helicopters and air tankers were fighting the flames.A shelter that had been set up by the American Red Cross at a Flagstaff middle school for residents displaced by the Hardy fire also was being used for evacuees from the Shultz fire.Fire officials did not know what sparked the second blaze. But a California man was arrested Sunday on suspicion of starting the Hardy fire by leaving behind hot coals at a campsite just outside the city.Randall Wayne Nicholson, 54, was arrested on a misdemeanor charge of burning of a wildland, city spokeswoman Kimberly Ott said. Nicholson, whose hometown was not immediately available, was being held on a $2,500 bond at the Coconino County jail. It was unknown if he had an attorney.Authorities said the Hardy fire started in a wooded area a couple of miles from downtown after Nicholson built a small campfire for either cooking or making coffee. Investigators believe he dumped coals from the fire on the ground before leaving the site."As far as we understand, this was not a deliberate act. It was a careless act," Ott said.The fire quickly spread up a hill and threatened homes in two neighborhoods. Crews worked overnight and Sunday to protect structures and establish a perimeter around the blaze. But Coconino County spokeswoman Joanne Keene said fire officials have not declared any part of the fire contained."The winds are expected to pick up, and the latest I've heard is about 30 mph so we're concerned about that," she said.Evacuation orders for 170 homes remained in place, and a park and popular bike trail were closed as a precaution, Keene said. The Little America Hotel also was briefly evacuated.The Hardy fire also sent smoke through parts of Flagstaff and caused traffic to back up on Interstate 40. Authorities said no homes or buildings had been burned.Heavy tankers and three aircraft were on standby in case ground crews needed help.Fires also had crews busy Sunday near Williams and in Colorado and New Mexico.High winds and rugged terrain kept ground crews and aircraft from getting close to a wildfire in southern Colorado's Great Sand Dunes National Park. The fire grew to 4,500 acres.In New Mexico, crews were making progress on the South Fork fire, which had charred more than 11,150 acres in steep, inaccessible terrain in the Jemez Mountains.Rick Ochoa of the National Interagency Fire Center in Idaho said officials had anticipated a much bigger fire season in the Northwest, but a series of moisture-bearing storms in the region lessened the fire activity at higher elevations. He said the opposite has been true in the Southwest."The Southwest had a wet winter and then the spring turned dry. Because we've had all of these storms up in the northwest, that's brought a lot more wind to the Southwest, so the combination of a dry and windy spring has increased the fire potential quite a bit in the Southwest," he said.