TRACY, Calif. -- Two people were questioned after a missing teenager apparently escaped captivity and ran into a fitness center Monday with an inch-thick chain shackled to his ankle police in Tracy, Calif., said.

Wearing just boxer briefs, the 17-year-old burst into an InShape Fitness Center at about 4 p.m., said Chuck Ellis, who works at the gym, told TV station KCRA.

Ellis said the boy looked scared and said, "Hide me, please hide me."

"He was hunkered down, terrified," Ellis said.

Covered in dirt or soot, the teenager was also bleeding on his back and had a significant cut on his arm, Ellis said. He said the boy started to talk some about what had happened, but his attention quickly returned to his captors.

"He started talking a little bit, and then just said, 'they're coming.' He was just so panicked that they were going to come to him," said Ellis. "The whole time we were with him, we were just trying to reassure him, not trying to question him."

The teenager told gym employees that he was taken from a Sacramento group home about a year ago, Ellis said.

Robinson said the boy was confused when first approached by detectives, unsure where he had come from and how long he was being held against his will. "The wounds he had and his physical condition as well as having a chain around his leg corroborated his basic statement that he was being held against his will," Robinson said.

Robinson said detectives planned to interview the unidentified boy, who was taken to Sutter Tracy Community Hospital, more extensively Tuesday when he is a "little healthier."

Robinson said authorities are questioning a couple in their 30s, but that they have not been arrested or charged.