"We don't have many details yet as they have taken her to a hospital for evaluation, but all appears at this point in time to be well," Sharette wrote.
Police later said Esquivel left her school after becoming upset with a teacher over an assignment. From there, she walked along 3100 South toward the mountains. She told police they "looked peaceful."
After sunset, Esquivel became disoriented and found a place to rest until morning.
Powell said officers followed up on tip received about 8:30 a.m. that the girl had been located in the area of 6200 South and 4600 West almost five miles from the school, which is located at 3636 W. 3100 South.
The girl was taken by ambulance to a hospital, where doctors treated her for hypothermia.
Her parents were at her bedside, police said.
Police do not believe foul played a role in Esquivel's disappearance.
Meanwhile, Sharette said the school also was reviewing its policies regarding student monitoring. "We have met as a team this morning to do an initial analysis of what we could do better to ensure our students' safety," she said.
Esquivel, described as having diminished mental capacity, was last seen about 3:30 p.m. Monday at the school.
Police had gone door-to-door late Monday in the neighborhoods surrounding the school but were unable to find a trace of the girl. Through the night, aircraft equipped with spotlights and heat-sensitive scanners also were used as part of the search.
"We have no indication she [was] a runaway," Powell said, adding that the girl, who is enrolled in her schools' special education program, had no previous history of deviating from her schedule and routines.
Tribune reporter Jim Dalrymple II contributed to this story.