GUWAHATI, India - Indian security forces stepped up operations to prevent further violence in Manipur state on Wednesday after a seven-year-old boy, his mother and a relative were burnt alive when a crowd set fire to an ambulance ferrying them to a hospital.

The boy was being rushed for medical treatment on Sunday night after he was shot amidst deadly ethnic clashes between tribal groups and the majority Meitei community in the northeastern state.

The Indian Army on Wednesday said it had launched operations in hill and valley areas across Manipur "to dominate sensitive areas and recover snatched weapons".

"Locals in possession of such weapons being urged to surrender them to the Security Forces for the sake of peace & harmony," the army said on Twitter.

The ethnic violence in the state began in early May when tribal groups clashed with the Meitei community, worried that the economic quotas and benefits granted to them would also be extended to the Meiteis.

More than 60 people have been killed and around 35,000 displaced since the rioting began last month.

More than 30 militants have also been killed by security forces.

Sunday's incident took place in the remote Iroisemba area in Imphal West district, when the ambulance ferrying the family was waylaid by a crowd of about 2,000 people, most of them from the Kuki tribe.

The boy's father also belongs to the same tribe, but was not with him at the time. His mother and the male relative accompanying him belonged to the Meiti community.

"The woman and man in the ambulance pleaded for mercy saying the little boy had bullet injuries but the mob refused to spare them and set it on fire," a police official told Reuters on the condition of anonymity.

The child's father, Joshua Hangsing, told local television Northeast Live that he is yet to receive the bodies of the victims.

"I have not yet received the dead bodies but I have heard that the three were charred beyond recognition with just a few bones left in the ambulance," he said.

(Writing by Sakshi Dayal; Editing by Angus MacSwan)