Christopher was believed to kill Wellington and the people and the situations they put him in caused him to have a sensory overload
"I do not like people shouting at me. It makes me scared..."(Haddon 4) Christopher can't stand people yelilng at him because he is unsure about what they're saying and what they are going to do.
Mrs. Shears came up to Christopher and Wellington while yelling at him to put him down. She then started to scream which Christopher also hated so he covered his ears and curled into a ball to calm himself down.
While one officer helped Mrs. Shears into her house, the other questioned Christopher as to why he was there and he got angry at Christopher so he started to yell at him.
Since the police officer doesn't know Christopher doesn't like being touched, When he was touched by the police officer, he hit him and that kicked off the sensory overload.
Too much was going on at once and in result, he blacked out.