An autistic boy was robbed, beaten up, and stripped at knifepoint in a city centre car park.

It was the first time that Curtis McDonnell, aged 16, had been to Manchester on his own.

He was attacked by three thugs on the 10th floor of the Arndale shopping centre car park.

The teenager from Blackley suffered a broken rib and head injuries which required a hospital scan after being kicked and punched.

After robbing him of his rucksack, mobile phone, and two pounds, the gang pulled off his trousers and shoes and threw them over a balcony.

Curtis was left in agony crawling to an escalator to try and get help and was ignored by several people until a concerned couple stopped to help and alerted police.

Now Curtis’ mother, Karen Hill, has hit out at the gang’s inexplicable cruelty and says the teenager’s confidence has been shattered.

She told the M.E.N.: “I feel disgusted. They have not only robbed him, they have taken away his self confidence.

“It was the first time he had been to town on his own. We thought he was just out near home with two friends.

“But we think they caught the Metrolink - Curtis had never been on a tram before.

“It shows how vulnerable and innocent he is - they were in the car park having a game of tig.”

Watch: Curtis' mum speaks about the attack

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The three thugs, who it is believed were caught on CCTV getting out of a lift at the car park, and later in the Arndale on an escalator, shouted to Curtis.

Karen, from Blackley, said: “He said ‘have you got a lighter mate’. Curtis would not have sensed any kind of danger and said ‘yes’ and walked over.

“They started rooting through his bag and then one said they were keeping his lighter.

“Then they shouted back they were only kidding, and Curtis went back. That is when the three of them surrounded Curtis and slapped him.

“Curtis lashed out at one of them and that’s when the bigger of three pulled out a knife and told him that if he hit back he would stab him.

“When Curtis’ two friends saw the knife they ran off. Curtis was pushed to the floor, punched, and kicked.”

The couple who found Curtis also alerted the car park manager who stayed with the boy until his father, David, arrived, and took him to North Manchester General Hospital.

Karen, 41, said: “He had a scan and we have to take him back to hospital if he feels sick or gets headaches. His lips were badly swollen and he is in pain with a broken rib.

“I don’t want those responsible to get away with it.

“Curtis has attended Our Lady’s High School in Blackley although he had one to one support. He is due to go to college in Openshaw, for entry into work courses, but now does not want to go after this. We had spent the last six weeks persuading him to go.

“I don’t think those who robbed him realise how much damage they have done.”

The two friends who were with Curtis also both have learning difficulties.

The mother of one said: “My boy is 15 but has the learning capacity of a child aged eight to eleven.

“When the attackers asked Curtis to come back for his lighter, my son and his other friend were worried and told him not to, as it was just a 60p lighter.

"But he did and the youths then started slapping him.“

"The youths were aged about 17, 18, 19, they threatened my son and the other boy that they would be stabbed too if they tried to help Curtis.

"They ran to get help and then came back with the NCP car park manager, who was brilliant and stayed with all three the boys until helped arrived.“I am still waiting for the police to come an interview my boy. The robbery badly affected all three boys.”

GMP confirmed they were investigating the robbery.