An Idaho woman who allegedly took her three children in a custody squabble may be in the Phoenix metropolitan area on the way to Mexico, authorities said Tuesday.

The FBI in Salt Lake City said an Amber Alert was issued Sunday morning for a 9-year-old boy and two girls, ages 5 and 7.

They said 35-year-old Bertha Sabala Guerrero lost custody of the three children last December after authorities say she left them with a woman she had just met. They were placed in foster care in Caldwell, Idaho.

The children are identified as 5-year-old Esmerelda Guerrero-Lopez, 7-year-old Mirella Guerrero-Lopez and 9-year-old Ubaldo Guerrero-Lopez Jr., according to an FBI press release. 

Authorities said Guerrero picked up the children for a 24-hour visitation Friday and failed to return them the following day. Caldwell police have obtained an arrest warrant for Guerrero for custodial interference.

The FBI said Guerrero and the children may be traveling in a gray or silver 1986 Pontiac 6000, 4-door sedan, with Nevada license plate number 389XPR.

They said Guerrero has family living in Phoenix and Mexico.

The Associated Press contributed to this report.