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(CNN) -- Mark Engle saw thick smoke billow through the air outside his Colorado home on Tuesday. From a window, he watched deer grazing in his backyard, driven out of the forest by flames that have devoured thousands of acres of land only a few miles away. His children's backpacks were placed by the door, stuffed with their favorite toys.
His family is packed and ready to leave in a hurry, Engle said. But they want to stay put, even though authorities have ordered residents in the area to evacuate.
Only three to four miles away from the home he shares with his wife and three children, a fast-moving wildfire has consumed nearly 43,500 acres in northern Colorado. The flames, which authorities said were caused by lightning, have destroyed more than 100 structures and left one person dead.
"There's a number of people like myself, (for whom) packing up and leaving when you have livestock and animals just isn't as easy as if you have just a house," Engle said.
He'd like to think he won't have to. Firefighters gained some control Tuesday, especially on the eastern flank, Larimer County Sheriff's Office spokesman John Schulz said.
President Barack Obama telephoned Colorado Gov. John Hickenlooper on Tuesday and said his administration is already making personnel, equipment and federal grants available to the state, said White House spokesman Josh Earnest.
As of Tuesday, there were 40 fire engines and 17 fire crews battling the blaze, said Bill Hahnenberg, the incident commander. Officials want to increase that to 100 engines and 34 crews by Wednesday, Hahnenberg said.
First measured at two acres early Saturday, the High Park Fire has grown exponentially in the time since, including more than doubling in size Sunday and again overnight into Monday.
But the nearby flames weren't Engle's most immediate concern. Police roadblocks prevented his family from getting supplies, he said.
"Even if we leave to get a gallon of milk they won't let us back in," he said.
Engle said he and his neighbors feel frustrated that there is no leeway.
"I parked on the side of the road and walked up to the officers to discuss whether or not I could pack up my animals and move them out then come back," he said. "But they told me if I leave, bar none, I would not be allowed to return."
Engle said the officers told him if he crossed the line, his wife and children would "just have to figure their own way out."
"They even told me it was a good thing I parked where I did because if I'd crossed I wouldn't be able to go back," he said.
Schulz, the sheriff's spokesman, said he can sympathize with residents' frustration, but that it would be "irresponsible" to allow anyone into an evacuated area.
He said the evacuation orders are mandatory, though the police won't force anyone to leave their home.
"If after we've evacuated the area and then they decide they're going to run to the store and get groceries and come back, well, no," he said. "We're not going to force you to leave, but once you're out you're not getting back in because we believe that area is unsafe."
The department does have special teams to go into evacuated areas -- when there is no eminent danger -- to retrieve livestock or essential items like medication that have been left behind, he said.
"If they don't leave, there is likely not going to be anybody available to come help them when the fire is on them," he said. "And we're not going to put firefighters or deputies at risk trying to come back into an area to save them."
One person has died in the fire: a 62-year-old woman identified by family members as Linda Steadman. Her body was found inside her burned home.
The "mother, grandmother, sister and wife perished in the cabin she loved," the family said.
A pre-evacuation is under way in an area covering at least 89 more homes, said Nick Christensen, executive officer of the sheriff's office. That means residents are being asked to prepare for an evacuation if one is ordered.
Some of those evacuated Monday could do nothing but watch as firefighters doused the dry, hilly terrain, hoping their homes would be saved.
But Kyle Ellis knew it was too late for his house.
He struggled to tell his young daughter why the fire moved so quickly, why they no longer had a house to go home to, CNN affiliate KUSA reported.
"Fire burns real fast, real hot, real dry," he said. He kissed the young girl on the cheek and told her she would get a new home.
CNN's Greg Morrison contributed to this report.