The suspects, aged 22, 25 and 26, were detained on Sunday in Walthamstow, east London, on suspicion of conspiracy to commit grievous bodily harm, West Mercia Police said.
The boy was in a pushchair when he was "deliberately attacked" at Home Bargains in Tallow Hill on Saturday, the Guardian reported on Monday. He suffered serious burns to his face and arm. The motive behind the attack was unclear, authorities said.
Doctors discharged the boy from hospital on Sunday.
A 39-year-old man from Wolverhampton had been arrested earlier on suspicion of conspiracy to commit grievous bodily harm and remained in police custody over the incident.
The leader of Worcester city council, Marc Bayliss, described the attack as "absolutely pure evil".
The MP for Worcester, Robin Walker, called it "horrific", and that the "shock will be universal". Police appealed for more information over the incident.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
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