"We can guarantee she is not with either parent, and she may possibly be in extreme danger," said Lt. Dawn Westerfield, Gary Police Department.
Chastinea Reeves was last seen at about 2 a.m. Monday in the 2000-block of Maine Street at her aunt's house where she went after her mother was the victim of a crime, police said.
"Two children came to my door a little after 2 a.m. and they said someone had come in, somebody had did something to their mom so they came here," said their aunt Kelli McMillan.
But as McMillan dialed 911, Reeves ran out the back door.
"When she run out the back door when the police come I just had to tell them, she ran out the back door. She got out of here," McMillan said.
Reeves is 5-feet-2-inches tall, weighs 130 pounds, and has black hair and brown eyes.
She was last seen wearing a grey T-shirt and black jeans.
Police said it was immediately unclear if the crime against her mother was related to her disappearance. It was also unknown whether she was walking, in a car, alone or with another person.
Police said she was not with her parents and did not attend school on Monday.
"Chas, if you out there, please come home. You're not in trouble. We just want to help," her aunt Kelli pleaded Monday night.
"Her mother was the victim of a crime. We don't know if she is in danger from that as well," Westerfield said.
Anyone with information is asked to contact the Gary Police Department at 1-888-58AMBER (582-6237) or 911.