LONDON - Three men have been arrested after a three-year-old boy was seriously injured in a targeted acid attack in Worcester, England, the police said Monday.

West Mercia Police said three men, aged 22, 25 and 26 respectively, were arrested in London on suspicion of conspiracy to commit grievous bodily harm. The motive for the attack is so far unclear.

The boy was in a pushchair when he was "deliberately attacked" at a retail shop in Worcester on Saturday afternoon. He was treated for serious burns to his arm and face, before being discharged from hospital on Sunday afternoon.

The long-term implications of his injuries are unknown, according to the police.

The acid attack shocked local communities as well as the media nationwide.

Britain has one of the highest rates of acid attacks per capita in the world, according to Acid Survivors Trust International (ASTI). It claims the country does not have "tight controls on acid sales" or "legislation specific to acid attacks".

ASTI's figures, quoting the police, reveal the number of recorded attacks has increased nearly three-fold from 228 recorded crimes in 2012 to 601 attacks in 2016.

Last year was widely regarded as the worst ever with more than 400 incidents reported in the six months to April 2017 alone.

There are plans to further restrict the sale of corrosive substances, but the attacks are still on the rise. Criminologists believe gang members may be swapping guns and knives for acid as a weapon of choice because possession is hard to monitor but its impact on victims can be devastating.