A six-year-old boy drowned in a river after his dad was bottled by a robber.

The shocking incident took place in St. Johann in Tirol, Austria, at around 4am on 29th August.

The German dad, 37, was reportedly pushing his son Leon in his buggy when, according to police, he was struck on the back of the head with a bottle by an unknown assailant.

He reportedly fell to the ground unconscious, whereupon Leon – who suffered from the rare genetic condition SYNGAP1, which results in severe learning disabilities – apparently wandered around disoriented.

But tragedy struck when he reportedly fell into the nearby Kitzbueheler Ache river and drowned. His cause of death was confirmed by an autopsy later the same day.

The crime was discovered when a passerby found the dad when he came to at around 5.20am.

Police said he could not remember what had happened but asked about his son. But by that point, Leon’s special-needs pushchair was nowhere to be seen.

Dozens of good Samaritans joined in the efforts to find the youngster, whose condition meant he was unable to speak.

But an hour later, the worst was confirmed when his lifeless body was pulled from the river.

Police believe little Leon climbed out of his pushchair on his own, unintentionally fell into the river and was swept 600 metres downstream, where he was found dead.

But investigators were baffled to find the dad’s mobile phone and wallet in the immediate vicinity of the crime scene.

And they were also puzzled as to why he was out with his son at such an unsocial hour.

However, local media have suggested it was because of Leon’s condition, which interrupted his sleep.

At the time of reporting, police had not yet spoken to the dad, who was in hospital and whose name has so far been withheld.

Police reported that Leon was an Austrian national.

The investigation is ongoing.