The incident took place yesterday when three girls were returning home in Rajeev colony from their tuition classes, said Sahibabad Police SHO Upendra Yadav.
Four youths identified as Ankit, Varun and their two friends made indecent gestures and passed lewd remarks on the girls who then raised an alarm, he said.
Upon resisting, the youths even threatened to rape them.
Following the commotion, several passersby gathered and caught hold of the duo and handed them over to the police. In the melee, two boys escaped from the spot, police said.