Updated

The Florida Department of Law Enforcement has issued an alert for two missing children believed to be endangered.

Trieu "Kiah" Firth, 2, and Chieu "Kristin" Quan Firth, 4, have been missing since Thursday, MyFoxOrlando.com reported.  They were last seen in Melbourne with their parents, James Firth, 43, and Mai Dang Firth, 31.

The Department of Children and Families (DCF) had been investigating alleged threats made by the children's parents to kill their daughters and then kill each other in a "suicide pact."

The family resides in Vietnam and traveled to the United States to obtain treatment for Kristin, who has autism. DCF officials said the parents were frustrated and distressed over the cost of the treatment, according to the website.

Before DCF could shelter the children, the family disappeared.  They were last seen near the Florida Institute of Technology.  James Firth has family in Florida, Michigan and Arizona.  The family may be traveling to San Francisco to board an international flight to Vietnam. They may be traveling in a 2002, silver Lexus SUV, FL tag number 612PGW.

Kiah was last seen wearing a pink dress with flower print and Kristin was last seen wearing a dark blue dress with a belt and a bow in the back.

Anyone with information is asked to call Melbourne police at 321-409-2205 or Florida Department of Law Enforcement at 1-888-FL MISSING (1-888-356-4774).

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