(HLNtv.com) -- The father of two Southern California children who went missing after their mother was killed pleaded Tuesday for their suspected abductor to release his daughter. 

A massive manhunt is under way for James DiMaggio, whom law enforcement authorities describe as a friend of the mother, Christina Anderson. 

The whereabouts of Anderson's children, Hannah, 16, and Ethan, 8, are unknown. Investigators believe they may be with DiMaggio, 40, the owner and sole resident of the burned home where Anderson's body was found, along with the unidentified remains of a child. 

"Jim, I can't fathom what you were thinking. The damage is done. I'm begging you to let my daughter go. You've taken everything else," Brett Anderson, the children's father, told reporters. 

"Hannah, we all love you very much. If you have a chance, you take it, you run. You'll be found," he said. 

The father did not mention Ethan in his remarks, prompting a reporter to ask San Diego Sheriff's Department Lt. Glenn Giannantonio whether the child's remains might be those of the boy. 

"We don't know who that is that was found in the rubble. It is a possibility that it's Ethan. It's a possibility that's another child that we haven't identified yet, or don't realize is missing yet," Giannantonio said. 

"Right now, we just don't know, and we're praying that it wasn't Ethan," he said. 

Authorities are following up on tips and casting a wide net for DiMaggio and the children. 

"We've received some information that either Texas or Canada may have been the destination he was heading to. Realistically, we don't know where they're going," Giannantonio said. "We're looking everywhere." 
Who is suspected of abducting them?
A massive manhunt is under way for James DiMaggio