( CNN ) Three teenagers from northwest London were released on bail Sunday after their alleged plans to travel to Syria led to their arrest . Two 17-year-olds boys and a 19-year-old man were arrested `` on suspicion of preparation of terrorist acts , '' the Metropolitan Police said . The investigation started on Friday , after police learned the two 17-year-olds were missing and were believed to be traveling to Syria . They were traveling with a 19-year-old , police said . British authorities shared intelligence regarding the 17-year-olds with Turkish officials on Friday , and that night , the individuals landed in Istanbul on a flight from Barcelona , Spain , a Turkish official told CNN . The teens were stopped , along with another person who had been regarded as suspicious by Turkish intelligence working at the airport 's risk analysis center , which monitors risky flights and runs checks on suspicious passengers trying to enter Turkey . Turkish authorities questioned the teens , the Turkish official said , and the Metropolitan Police said the three arrived back in London shortly before midnight Saturday and were arrested . `` When we have intelligence shared with us there is no problem . We stop them and directly deport them . And of course Turkish intelligence is always on the lookout as well , '' the Turkish official said . Turkey on Thursday arrested a person who worked for an undisclosed nation 's intelligence service on suspicion of helping the girls , according to Turkey 's foreign minister . On Friday , a Turkish television network aired a video purportedly showing the girls preparing to cross the Turkish border into Syria . CNN 's Eliott C. McLaughlin , Arwa Damon and Karen Smith contributed to this report .
Three teens were released on bail in London , where they face terror charges . Comment: