One reason the beating was not stopped was the bystander effect.
On March 16, 1993, a 16-year-old Somali Shidane Abukar Arone was caught trespassing by Canadian soldiers deployed in his country. He was found hiding in a portable toilet and claiming he was looking for a lost child. The patrolmen took him to an underground bunker in the Canadian encampment where he was brutally tortured to death.
Arone's screams for help were heard by more than 80 soldiers but nobody came to his rescue. The soldiers were playing games, some saw Arone being tortured and commented on him being 'a nice trophy'.
Nobody helped the boy because of the bystander effect. It is a social and psychological phenomenon in which individuals are less likely to offer help to a victim when other people are present. The presence of others discourages an individual from intervening in an emergency situation. This effect is attributed to so called diffusion of responsibility ( a person is not willing to help because he thinks others should do it first).