CCTV captured the girls passing through security at Gatwick Airport
Fears are growing for the safety of three east London schoolgirls who police believe are trying to cross the Turkish-Syrian border to join the Islamic State terrorist group.
Shamima Begum, 15, Kadiza Sultana, 16 and their unnamed 15-year-old friend flew from Gatwick to Turkey on Tuesday.
Police have issued an urgent appeal for help in finding them, suggesting they are "extremely vulnerable".
The trio are friends with a fourth girl who travelled to Syria in December.
Police released CCTV footage of the three girls at Gatwick Airport
Abdul Samid, a parent governor at Bethnal Green Academy, which all four girls attended, said there was "absolutely not" any radicalisation at the school.
"I'm 100% confident - with the head and the senior leadership team and the whole school - that we've done everything to put in measures that safeguard all the children that attend the school," he said.
He said he did not believe the girls were trying to get to Syria.
"I still don't believe that they are going anywhere other than a holiday - because this is how they were dressed and this is how they looked and this is how they packed," he added.
However, Metropolitan Police Commander Richard Walton said he believed the girls intended to travel to Syria, where they would be "in grave danger".
He said he hoped they would "hear our concerns for their safety and have the courage to return now, back to their families who are so worried about them."
Police hope the girls may still be in Turkey, as severe winter weather is currently affecting transport links in the country.
The three teenage girls were last seen on Tuesday morning, when they told their parents they were going out for the day, police said.
CCTV at Gatwick airport captured the girls as they passed through security, before boarding a Turkish Airlines flight to Istanbul.
Shamima is possibly travelling under the name of her 17-year-old sister Aklima Begum, police said.
The third girl is not being named at the request of her family.
Police have issued a description of the three girls:
Kadiza Sultana, aged 16, is the oldest of the trio, who are all in the same school year
Shamima Begum, 15, could be travelling under the name of Aklima Begum, police said
It is thought more than 50 British women have travelled to Syria via Turkey to join Islamic State to become so-called "jihadi brides".
Sara Khan from Inspire, an organisation which works to counter extremism and gender inequality, said girls were often convinced to travel to Syria by young jihadi men they met online.
"These are young men who will often befriend these girls over a number of weeks," she said.
"They will shower praise and flattery on them, win their affections, try and convince these young girls that I as a man I love you."
Those with information can call the free Anti-Terrorist Hotline number on 0800 789 321.