A boy, who threw acid on a 13-year-old girl for rejecting his proposal, was arrested in Chembur in northeast Mumbai on Wednesday.
Two other schoolgirls, who were standing nearby, were also injured. The police said the injured were out of danger.
"The boy, Arjun, threw a balloon filled with acid at the girl, a class eighth student of Louretto Convent in RCF Colony. She was on her way to the school," Senior Police Inspector P D Ulvekar said.
The police also arrested the boy's employer, a 32-year-old caterer, who had instructed the boy to throw acid on the girl.