A German airline Lufthansa aircraft is pictured at Munich’s airport Sept. 19, 2014.

Three American teenage girls from Colorado were stopped in Germany over the weekend while they were en route to Syria to join the Islamic State of Iraq and Syria (ISIS), U.S. authorities said on Tuesday.

The girls from suburban Denver in Colorado are two sisters, ages 17 and 15, and their 16-year-old friend of ethnic Somali origin.

They were reported missing after they skipped school on Friday, but their families were unaware of their whereabouts, the Associated Press quoted Glenn Thompson, bureau chief of the Arapahoe County Sheriff’s Department, as saying.

FBI agents reportedly stopped the girls at the Frankfurt airport, Germany and returned back to Colorado.

“The juveniles are safe and reunited with their families,” FBI spokesperson Suzie Payne in a statement, according to 9News Denver.

A U.S. official told NBC News that the girls were headed to Syria to join Islamic militants.

Investigators were checking the girls’ computers for evidence they might have been radicalized online. But an official who described the case as “concerning” said available information provides enough evidence to ascertain that the girls were headed to Syria.

The Arapahoe County missing person’s report provides details of the girls’ movement from Colorado to Germany.

They said they stayed in the Frankfurt airport for an entire day before being detained, questioned and returned to Denver, where they were further questioned by the FBI and sent home.

They told authorities they had gone to Germany for “family” but wouldn’t elaborate, according to the Associated Press.

Suspicion arose when the sisters’ father realized his daughters were gone, along with $2,000 and their passports.

The 16-year-old girl’s father became concerned when he got a call from her high school saying she hadn’t reported to class, according to the police reports.

The families reported no prior problems with the girls.

Deputies closed the missing person’s case Monday after they learned the girls had been returned.

A man who answered the door at the sisters’ home in the Denver suburb of Aurora identified himself as a family member but said he had no comment.

The announcement comes one month after 19-year-old Shannon Conley of Arvada, Colorado, pleaded guilty to charges that she conspired to help militants in Syria.

 
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