(NewsNation) — An Amber Alert has been issued for two missing Idaho teens whose disappearance appears to be tied to their religious beliefs, according to the Jefferson County Sheriff’s Office.

On Sunday, 13-year-old Allen Fischer and 15-year-old Rachelle Fischer were reported missing from their Monteview home by their mother.

Authorities said Tuesday they’ve found no concrete evidence the initial vehicle used to transport the children was involved. However, police have narrowed down a time frame during which the children went missing to the hours of 6 p.m. and 8 p.m. Sunday.

Additionally, authorities said they’re now unsure if the children have left the immediate area or are still nearby.

The teens are believed to possibly be in the company of their adult siblings headed to a Fundamentalist Church of Jesus Christ of Latter-Day Saints community in Trenton, Utah.

The teens’ mother, Elizabeth Roundy, who has full custody, told NewsNation local affiliate KTVX that the family had left the FLDS community about five years ago. She is now concerned that adult siblings of the teens, who are active members of the faith, have taken them.

Elintra Dee Fischer, 18, an older sibling of the teens, was reported missing on Jan. 1, 2023, and has yet to be located. Roundy believes the children left with Elintra to fulfill their religious obligations.

Allen Fischer and Rachelle Fischer were last seen wearing traditional FLDS clothing. Rachelle was reportedly last wearing a dark green prairie dress, while Allen was seen wearing a light blue shirt with jeans and black slip-on shoes before the alleged abduction.

Holding out HELP, an organization that helps survivors of polygamy, is expressing concern for the missing teens, citing fear that the FLDS church is trying to get teens to abide by its rules.

Jefferson County Sheriff’s Office asks anyone with information about these missing juveniles to contact their dispatch center at 208-745-9210, option 7, or call 911 for your local law enforcement.