A 20-year-old woman was allegedly molested by four youths at Beadon Street in north Kolkata, the police said today.
After the woman raised an alarm, locals rushed in, rescued her and caught hold of one of the youths.
He was handed over to the police and she filed a complaint about the incident last evening.
After interrogating the youth, the police later arrested one of his friends while two other accused were at large.