The juvenile was apprehended red-handed around midnight after the owner Tent House called the police, said a senior police officer.
The girl had allegedly sneaked into the wedding and was trying to pick one of the shagun envelopes, police said.
She was produced before JJB and sent for 14 days to an observation home.
Police is investigating whether the juvenile has any links to the gang that has sent officers into a tizzy by fleeing with valuables from weddings.
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