Fla. kids, parents missing after threatened murder-suicide, authorities say

(CBS) Florida authorities are searching for two young children whose parents allegedly threatened to kill them in a murder-suicide if their 4-year-old daughter's autism did not improve by the time their money ran out, the Orlando Sentinel reports.

James Firth, 43, and his 31-year-old wife, Mai Dang Firth, were last seen with their daughters,  2-year-old Trieu "Kiah" Firth and 4-year-old Chieu "Kristin" Quan Firth, on Thursday near Florida Institute of Technology in Melbourne, according to the newspaper.

The Florida Department of Children and Families said the family came to the U.S. from Vietnam to seek medical treatment for Kristin. The agency planned to take the girls into custody, but police said the family disappeared before investigators could find them.

The New York Daily News reported that the Firths allegedly said they would murder the children and then kill themselves if treatment was too expensive or failed to work. The Florida Institute of Technology is home to the Scott Center for Autism Treatment but a spokeswoman wouldn't confirm whether they were seeking treatment there, according to the Daily News.

Authorities said James Firth has relatives in Ormond Beach, Fla., as well as relatives in Michigan and Arizona, the Sentinel reported. The family may be driving to San Francisco in a 2002 silver Lexus SUV to hop a plane back to Vietnam.

Anyone with information is asked to contact Crimeline at 1-800-423-8477 or the Florida Department of Law Enforcement at 888-356-4774.