As the Syrian civil war enters its sixth year of bloodshed, thousands of children are losing their parents, their education and their homes.

Many remember nothing before the brutal conflict, which is leaving invisible scars on those fleeing fighting, bombardment and the atrocities committed by Isis.

A study by Save the Children warns that the situation was at a “tipping point” for mental health, with drastic intervention needed to help the youngest and most vulnerable Syrians who will be charged with rebuilding the country.

Even those who have fled to safety with their families as refugees are suffering “toxic stress”, which has a life-long impact on mental and physical health.

These are the stories of six children battling to recover from their trauma.

Mohammed, eight

“I am afraid by the war in Syria. It frightens me a lot to think about men surrounding me and pointing their weapons at me.”

Save the Children presents Mohammed's story of fleeing the Syrian conflict

When Mohammed was five, his father was killed by a sniper. He and his siblings saw the body in their local mosque but as his sister became hysterical, Mohammed showed no reaction.

The trauma became apparent as he became very introverted, developed a stammer, and started bed-wetting.

Since fleeing to Turkey, Mohammed has displayed aggressive and sadistic behaviour towards animals and people, including attacking his brother and mother and killing a kitten by throwing it from a building.

The eight-year-old now lives at a residential centre for children in Turkey, near the Syrian border.

Ahmed, nine

“I don’t like the planes, or the shells, or bombs, or mines. Some of them are underground, so you might be walking along and the mine explodes and then you die.”

Save the Children presents Ahmed's story of fleeing the Syrian conflict

Ahmed’s father died during shelling when he was seven and the corpse was brought back to the family's home.

He and his sisters didn’t talk for several days after seeing it, later moving to another village but being forced to flee after heavy bombardment.

During one attack, Ahmed became separated from his mother and one of his sisters. While they crossed into Turkey, Ahmed and his sister ended up following a relative to Isis’ de-facto capital of Raqqa.

The little boy was forced to watch the group’s beheadings, seeing dead bodies, heads on spikes, lashing and several other brutality in the streets.

When he was reunited with his mother in Turkey he was stammering so badly that she had difficulty understanding him.

He was wetting himself, had trouble sleeping, and would lash out at his family - beating his sisters and even his mother.

After almost one year living in a residential centre for mothers and children in Turkey, his mental health has improved.

Razan, seven

“I like to be alone, to be able to go out and no one kidnaps me. And for there to be no fighters or anything, and no bombing.”

Save the Children presents Razan's story of fleeing the Syrian conflict

When the war broke out, she had one brother and six sisters, including her favourite – Aya.

The two small girls were adored by their father, who took them for rides on his motorbike and showered them with gifts but one year into the war, he was killed by a sniper.

After seeing his corpse at the mosque, Razan stopped speaking and became very withdrawn.

Her family fled their home following bombardment, only to be displaced more than ten times in the same city.

Eventually, they ended up staying with relatives in a village but one day, the house they were staying in was bombed.

In pictures: Children play underground in Syria Show all 8 1 /8 In pictures: Children play underground in Syria In pictures: Children play underground in Syria A child plays in the ball pit at the 'Land of Childhood,' an underground playground in a besieged town in Syria Unicef In pictures: Children play underground in Syria Abdulaziz, 10, plays in the 'Land of Childhood' underground playground in Syria Unicef In pictures: Children play underground in Syria Boys look through a show window inside the tunnel that provides a safe passage for children between the two basements that form the 'Land of Childhood' in a besieged town in Syria Unicef In pictures: Children play underground in Syria Children play at the underground 'Land of Childhood' in a besieged town in Syria Unicef In pictures: Children play underground in Syria Two girls play at the 'Land of Childhood' underground playground in a besieged town in Syria Unicef In pictures: Children play underground in Syria Children on the ride on a ferris wheel at the 'Land of Childhood', an underground playground in a besieged town in Syria Unicef In pictures: Children play underground in Syria Seven-year-old Massa at the "Land of Childhood" underground playground in a besieged town in Syria Unicef In pictures: Children play underground in Syria Children wait in line to buy sweets at the 'Land of Childhood,' an underground playground in a besieged town in Syria Unicef

Razan was pulled from the wreckage alive but her mother and younger sister didn’t survive, and she witnessed horrific scenes of corpses and body parts in the local hospital.

She had shown signs of children after her father’s death she showed signs of trauma, becoming terrified of blood and panicking when she saw people crying.

Then after losing her mother and sister, Razan became aggressive towards her eldest sister who was caring for her, started bed-wetting, hallucinating and began to have trouble differentiating between fact and fiction.

She now lives at a residential centre for children in Turkey, near the Syrian border.

Hassan, nine

“I dream of a big bird, bigger than me: that I can ride it and fly away. I dream that I can fly, fly fast away into the sky.”

Save the Children presents Hassan's story of fleeing the Syrian conflict

When he was six, fighters stormed his house and shot his father dead at point blank range as the terrified boy was hanging onto his leg.

His family fled to a village but in a horrific accident that winter, his mother and sister caught fire in front of him while attempting to fill a stove.

Hassan’s sister died within hours but his mother survived, suffering such serious burns that he was unable recognise her for some time afterwards.

They took eight months to leave Syria, now living in Turkey, but Hassan has become introverted and occasionally violent.

Nesreen, nine

“When Syria didn’t have any planes, it was a beautiful place. But as soon as the aeroplanes came, they destroyed Syria, and turned it into rubble.”

Save the Children presents Nesreen's story of fleeing the Syrian conflict

She and her family fled from the rebel stronghold of Idlib to Turkey at the end of last year, having witnessed people killed in government and Russian air strikes

The bombardment felt continuous and the children were unable to sleep. Many of their friends and cousins died in explosions.

During their journey to Turkey, they were shot at and a four-year-old child whose family they were travelling with was hit in the head, dying in front of them in his father’s arms.

Nesreen and her siblings have already shown signs of psychological recovery in Turkey.

Abbas, seven

Save the Children presents Adira's story of fleeing the Syrian conflict

Abbas and his five-year-old sister Aya arrived in Turkey last year with their parents.

He suffers from cerebral atrophy and violent epileptic seizures, leaving him unable to walk or talk and requiring round the clock care.

The family originally fled their home in Palmyra when Isis invaded in 2015.

Abbas’ mother, Adira, wanted to travel to a nearby city so she could continue working as a teacher, and her son could get the healthcare he needed but they could not get past Isis checkpoints and headed towards Jordan instead.

A suicide bomber hit the border camp they lived in four months later, forcing them to travel to Turkey in a journey that took 21 days.