MOLINE, Ill. (AP) - Authorities have issued an Amber Alert for two young Moline children reportedly taken at knifepoint from their home.

Moline police say a man believed to have been their noncustodial father, 36-year-old Delfino Sierra took the children early Sunday morning while a 13-year-old nephew was baby-sitting them.

The missing children were identified as 1-year-old Judith G. Sierra and her 6-month-old brother, Delfino Sierra Jr. When taken, Judith was wearing a pink princess T-shirt and her brother was wearing a Winnie The Pooh T-shirt.

Police say Delfino Sierra Sr. is not married to the children's mother and is also known by the aliases Jesus M. Carrion and Jesus M. Melendez. His vehicle was found outside a residence where he had been staying, but neither he nor the children were there.