UPDATED 9-13-11 2 p.m. Three of the four juveniles who escaped from the Byron Boys Ranch last evening are back in custody. According to Jimmy Lee of the Contra Costa County Sheriff’s Office, the three boys, all 14, were arrested by Antioch police at a Walmart around noon.

The fourth escapee, a 15-year-old black male with a conviction for a violent offense, is still at large. According to Lee, the boy is 6 feet 3 inches, weighs approximately 300 pounds and is mentally challenged. He has black hair and brown eyes.

The Contra Costa Office of the Sheriff had issued a shelter-in-place alert Monday night for residents of Discovery Bay and Byron after the four boys escaped from the ranch around 8 p.m. The alert was issued about 11 p.m. and was lifted at 5 a.m. Tuesday following an overnight search of the area around the facility, which is located on Bixler Road.

Those who have seen the remaining escapee, or noticed suspicious activity or individuals, should call the Sheriff’s Office at 925-646-2441.