Authorities in Roanoke County, Virginia, continue to search Wednesday for three missing children — a 6-year-old boy, a 6-year-old girl and a 21-month old boy — after the father turned himself in.

John Varion Allison, 34, surrendered to an attorney Wednesday morning after police issued felony warrants for him and his wife, Ruby Marie Allison, 35, for the abduction of their children. The children are believed to be with their mother, but police are not ruling out the possibility that they have been given to some other party.

Police say that John Allison has not provided information.

An Amber Alert remains in effect for the Allison children: Cameron, 6, Emma, 6, and Colin, 21 months. All three are Caucasian with brown eyes. Cameron and Emma have brown hair while Colin’s is blonde. Authorities believe the children to be in “extreme danger.”

Police are searching now for a maroon Chevy Suburban that is believed to be connected to Ruby Allison. She is described as 5-foot-3 with brown hair and eyes.

Virginia State Police and the U.S. Marshals have joined the investigation, as well as officers from the neighboring Danville and Franklin County Sheriff’s Departments.

Authorities are asking anyone with information pertaining to the case to reach out. The Roanoke County Police can be reached at either (540) 777-8798 or (540) 777-8799. The State Police can also be reached at #77.

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In this photo a teenager volunteers and hands out flyers for a missing boy. Getty Images