(CNN) The little boy looks barely old enough to walk, let alone understand the dark world he's now inhabiting.

He should be toddling around a playground with his friends. But instead, he wears a black balaclava, crouched down in a desolate street with his tiny hands clenched around an AK-47.

He pulls the trigger and the recoil of the shot knocks him back, his limbs unable to control the rifle. An adult takes the weapon from the boy's hands as he stands up and steps away, casting a blank glance into the camera.

It's just one of the many videos that ISIS -- the Sunni terror group that has declared an independent Islamic state stretching from northern Syria to central Iraq -- has produced to boast of its youngest "recruits."

And as the radical Islamist group strengthens its hold on this huge swath of land in the heart of the Middle East, it is cramming its warped ideas into minds that are often too young to understand.

Mohammed, whose name has been changed out of fears for his safety, was one of them. He has now fled to safety in Turkey, but was just 13 when ISIS said he should attend one of their children's camps in northern Syria.

"My friends and I were studying at the mosque, and they taught us that we should enrol in jihad with the [Islamic State]," Mohammed told CNN. "I wanted to go, but my father did not allow me to."

When ISIS found out that Mohammed's father had prevented him from attending, the militants sent a patrol to their house.

"[They told me] 'if you prevent Mohammed from coming to the camp, we will cut off your head,'" his father, who declined to be named for this story, told CNN.

So off Mohammed went to the camp.

"For 30 days we woke up and jogged, had breakfast, then learned the Quran and the Hadith of the Prophet," Mohammed says. "Then we took courses on weapons, Kalashnikovs and other light military stuff."

Some of the militants at the camp were kind, joking and laughing with the younger recruits. Others made the boys watch hideous things.

"They used to bring young [kids] to the camp to lash them," Mohammed says. "When we go to the mosque, they order us to come the next day at a specific time and place to [watch] heads cut off, lashings or stonings."

"We saw a young man who did not fast for Ramadan, so they crucified him for three days, and we saw a woman being stoned [to death] because she committed adultery."

Mohammed says he understood some of the lessons taught at the camp -- like the importance of prayer and fasting -- but didn't understand words like "infidels," and why he should fight them.

The boys would take oaths of allegiance to ISIS' leader, Abu Bakr al-Baghdadi, and were considered ready to fight once they completed the religious and military courses taught at the camp.

Mohammed's father, terrified for his son, tried to visit him several times, but was turned back by guards who told him that the boy wasn't there, or on patrol somewhere else.

"He is only a child, they might make him a suicide bomber and [convince him] that will be in paradise and stuff like that," he said. Despite his fears, Mohammed's father expressed doubt that the militants' lessons would truly stick in his son's mind.

"How can a child like that be convinced? Where is the conviction in that? He is a child, it's not possible," he said. "He just saw his friends and kids his age went to the camp, so he wanted to go with them for entertainment. They thought war and guns were entertainment."

Mohammed's father was eventually able to pull him out of the camp, and the family fled to Turkey.

Now Mohammed doesn't know what to do. He doesn't want to go back to school -- he thinks he's too old for that now -- and thinks he might like to learn the trade his father practiced before they were forced to flee their home, fearful of what ISIS militants would make him do.

Mohammed says one of his friends at the camp has been killed on the front lines of ISIS' war with more moderate rebel groups fighting to topple the regime of Syrian President Bashar al-Assad.

"He was martyred in Deir Ezzor when he fought the Free Syrian Army with ISIS," Mohammed says. "He was my age, 13 or 14 years old."

ISIS may preach absolute fealty to Islam, but Mohammed doesn't recognize the militants' message in his own understanding of his religion.

"I love my religion because I am a Muslim," he said. "And I used to go with my father for the prayers before ISIS came. But my father has taught me that religion is not about fighting, but it is about love and forgiveness."

Mohammed and his family are safe now. But as ISIS spreads its tentacles across the region, an increasing number of Syrians have nowhere to hide -- and the group's murderous drive to convert everyone they encounter knows no age limits.