A fan zone was set up to allow those unable to get to the game in Cardiff to take in the European showpiece as the Bianconeri faced Real Madrid.
In contrast to the excitement which filled the area before the game, the end of it was followed by a wave of fear as a stampede ensued.
The Turin prefect said in a statement that the large crowd "was taken by panic and by the psychosis of a terror attack” as a result of a surge caused by a loud noise which was initially feared to be a bomb.
With thousands looking to flee the area in Piazza San Carlo, some supporters were trampled or crushed against safety barriers.
Three of those in attendance were to suffer serious injury, though, including a seven-year-old boy who is reported to have suffered head and chest trauma.
A 66-year-old man was also hospitalised with chest injuries, while a 38-year-old woman went into cardiac arrest.
In total, some 1,527 people were injured.
The collapse of a railing, combined with firecrackers being set off, is said to have generated the noise which sparked the panic.
"They were shouting and pushing, and it started a stampede," a witness was quoted as saying by ANSA.
"It was like being at Heysel," one said, referring to the stadium disaster before the 1985 European Cup final between Liverpool and Juve which claimed the lives of 39 fans.
Video footage from the fan zone shows a sudden rush in the middle of the crowd after Cristiano Ronaldo’s second goal for Real Madrid, which put the Spanish side 3-1 up on the night.
They would go on to add a fourth in stoppage-time to secure back-to-back successes in Europe’s premier club competition.