Three teen girls from Arapahoe County told their parents they were on their way to school Friday morning, but within hours they were flying overseas potentially seeking to join Islamic State militants, officials said Tuesday.

The girls, two of them sisters of Somali descent and another of Sudanese descent, were stopped at an airport in Frankfurt, Germany. One of their families reported that $2,000 was missing after the girls fled with their passports, the Arapahoe County Sheriff’s Office said.

“The families indicated they didn’t know where they were at and they did not know where they were going,” said sheriff’s Bureau Chief Glenn Thompson.

Suzie Payne, a spokeswoman for the FBI in Denver, said agents “assisted with bringing the individuals back to Denver. The juveniles are safe and reunited with their families.”

Payne declined to comment further, including providing the names or ages of the girls.

A U.S. official told The Associated Press that the girls were headed to Turkey en route to Syria and that investigators are reviewing evidence, including the girls’ computers.

Another U.S. official called the case “concerning” to the community and to the country, according to the AP report.

The official said the evidence gathered so far made it clear that the girls were headed to Syria, although the official said investigators were still determining what sort of contacts they had in that country. The official said investigators would be trying to figure out whether there were “like-minded” friends and acquaintances in the girls’ social circle.

The officials spoke to The AP on condition of anonymity because they were not authorized to discuss the ongoing investigation.

A spokesman for the Somali family told The Denver Post that the girls are in good condition and the family picked up the girls from Denver International Airport on Monday.

The spokesman provided only his first name, Asad.

He spoke outside the Highland Square Apartments, where several members of the news media had gathered Tuesday night.

Asad said the family was nervous about all of the media attention and still has its own questions about the events of the past few days.

Asked whether the girls bought their plane tickets, Asad said: “They bought the ticket. That’s what we think. We don’t know for sure. That’s why we don’t want to come out and make a statement.”

A report compiled by the Arapahoe County Sheriff’s Office detailed the girls’ actions and movements. The document was filed in connection to a runaway-children report by the father of the Somali girls.

“The girls explained that they stole $2,000 and their passports from their mother,” the report said. “They then went to DIA with another unidentified friend of theirs and flew to Germany. They arrived in Germany and stayed in the airport for an entire day.”

The report said police in the Frankfurt airport detained the girls then put them on a plane back to Denver, where they were met by FBI agents.

When a sheriff’s deputy on Monday went to their home to check on the girls, the deputy found them asleep in their bedroom. Their mother woke them up to speak to the deputy, the report said.

“I asked them why they went to Germany, and they said, ‘Family,’ and would not elaborate on any other details about their trip,” the deputy wrote in the report.

Authorities said they are very concerned for the safety of the girls, who are students in the Cherry Creek School District.

The sheriff’s office said it took runaway-children reports from both families on Friday evening. One family reported their 17- and 15-year-old daughters were missing, while another said their 16-year-old daughter was missing.

Thompson said the first report was taken at 6:30 p.m. Friday and the second was taken four hours later.

“The indications are that they were last seen earlier that day,” Thompson said. “Last contact was at about 10:30 a.m.”

Thompson said the sheriff’s office did not contact the FBI and that they have not been involved in the case since taking the initial report.

According to the report taken by the office, the two sisters told their father they were sick and were going to the library Friday morning and never returned.

Also, the father of a friend of the sisters’ came over to their house and told the other father that his daughter, too, was missing and that she had taken her passport.

The father of the two girls then discovered that his daughters’ passports were missing as well. When he tried contacting one of his daughters on her cellphone, she did not answer, the report said.

The Sudanese teen’s father told investigators his daughter’s school called him to report that she had skipped a class, the report said.

When he called the teen to ask where she was, she told him that she was just running late, although she never came home.

The man told investigators his daughter “has always been a good kid and he has had no real problems with her,” the report said.

Malak Eldie, 34, a Sudanese immigrant, said the Sudanese girl is new to the community, possibly from Minnesota.

“They got her to go by saying, ‘If you do this, it will good for Islam,” Eldie said. “She didn’t go to fight America.”

Police in Aurora referred all inquiries to the FBI.

The Colorado U.S. attorney’s office declined to comment.

The news of the three teens comes just months after Shannon Maureen Conley, 19, of Arvada, was arrested at DIA as she was about to embark on a similar route to try to join the Islamic State militants.

Conley, who was arrested by federal agents as she attempted to board a plane on her way to Syria, pleaded guilty to a charge of providing material support to al-Qaeda and affiliates, including the Islamic State.

Conley is scheduled to be sentenced Jan. 23, when she faces up to five years in a federal prison and a $250,000 fine.

Tuesday’s revelation has shaken the tight-knit Somali community in the Denver area as members tried to make sense of the events.

“Everybody is worried now about their kids,” said Amina Ali, a Somali immigrant, as she sat with her 12-year-old son at a community learning center Tuesday night.

“We want to know who recruited them and if they are in Denver or someplace else.”

Jesse Paul: 303-954-1733, jpaul@denverpost.com or twitter.com/JesseAPaul

Staff reporter Carlos Illescas and The Associated Press contributed to this report.