The three boys are students of Ekalavya Model Residential School at Laing in Odisha's Sundargarh district and had been to the eatery for food after sightseeing at nearby Mandira dam on Sunday, police said today.
The shopowner Chengda Ekka had allegedly found one of the boys holding a boiled egg and suspecting he was trying to steal it scolded them and then beat them, the police said.
The shopwner was arrested yesterday on the basis of an FIR lodged with the police, said Inspector in-charge of Rajgangpur Police Station S K Sethi.
The trio was rushed to Rourkela Government Hospital for treatment, he added.