A DESPERATE mum screamed "what have they done to my baby?" after thugs hurled acid in her three-year-old son's face as he sat in his pram.
Police have arrested three men aged 22, 25, and 26 in London - 130 miles away from the attack in Home Bargains in Worcester where the toddler was left with serious burns.
A forth man, aged 39, from Wolverhampton, was arrested following the attack on Saturday afternoon and remains in custody.
All four are being held on suspicion of conspiracy to commit grievous bodily harm.
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Horrified witnesses described a woman screaming for help as a "skinny white guy" fled the shop.
One shocked onlooker the mum was later seen with her head in her hands screaming: "My baby, my baby, what have they done to my baby?"
The witness added: "She was in floods of tears and people from the shop were telling her they had called an ambulance and her child would be well looked after."
The child was rushed to hospital with serious burns but has since been discharged and is back with his family .
But police said the long-term effect of the toddler's injuries are not yet known.
Detective Inspector Tony Garner said: "We'd like to thank everyone who shared our appeal over the weekend and contacted us with information. All of this is helping us to build up a better picture of this incident.
"We're continuing to urge anyone else with information to contact us."
The incident occurred at around 2.15pm in Home Bargains at the Shrub Hill Retail Park in Worcester on Saturday.
Although a racial motive has not been ruled out, detectives have said the attack is not believed to be linked to an English Defence League march which took place nearby.
A worker at a nearby hardware store said: "It's just disgusting. They told me he was covered in some kind of spray."
The busy retail park was filled with families and children on Saturday as they enjoyed the start of their summer holidays.
Donna Bird, who runs a city centre pub, said: "It's sickening to think that someone would do this, let alone to a three-year-old defenceless child. Nowhere is safe anymore.
"To think that this happened when you're going shopping or just going out about your normal day. I hope he makes a full recovery, must be heartbreaking for his parents."
Eyewitness Rachel Bryant, 22, said: "I'd been shopping with my mum and were heading to Home Bargains when there were loads of police and ambulances. I saw a woman crying and being comforted by police. I didn't know what it was all about.
"When I heard about the little boy being attacked with acid I couldn't believe it.
"It's horrendous to think something like this could happen to a little boy in the middle of a shop on a Saturday afternoon."
Cops were seen scouring bins and looking under cars yesterday as they continued hunting for the container used in the acid attack.
Shocked shoppers have described seeing police cars and ambulances dashing to the shop.
Dean Carey, 22, assistant manager at the store, said: "Events happened yesterday, police knew what happened and we are working with them.
"Everything is fine, everything is nice and safe for everyone, the staff are all fine. The incident happened but now we have moved on."
Worcester MP Robin Walker said: "The shock will be universal. Anyone conducting such an attack on a small child is just appalling.
"It's an issue which rightly there has been a lot of concern in Parliament and a move to toughen sentences for any kind of acid attack.
"But particularly the nature of this being a small child is very concerning indeed.
"At this stage the key thing is for the police to act quickly and see if they can track down the perpetrator and understand what's behind it, because it is an unthinkable thing to happen."
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Worcester City Council leader Marc Bayliss branded the attack "absolutely pure evil".
He said: "I have never heard of an acid attack in Worcester so this is absolutely not something we have any experience of."
Anyone with information should call 999 quoting incident 442s of 21 July 2018. Alternatively, call Crimestoppers, anonymously on 0800 555 111.
UK HIT BY SURGE IN MENACE
THE UK has seen a surge in reported acid attacks, with numbers soaring from 228 in 2012 to 601 just four years later.
We now have one of the world’s highest rates of attacks per capita, according to Acid Survivors Trust International.
Last year was widely regarded as the worst with more than 400 incidents in six months.
One saw Arthur Collins throw acid in a nightclub in Hackney, East London — injuring 20 people and leaving many victims with permanent scars.
Collins, ex-boyfriend of Towie star Ferne McCann, was given 20 years’ jail.
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