Prodip Choudhury, the officer in-charge (OC) of Dergaon Police Station, said no complaint was registered in the first 12 hours of the attack.
The main culprit Niraj Das alias Kola Loraa, a drug peddler, was said to be a hardened criminal against whom several cases are registered in various police stations.
The AASU set a 24-hour deadline before the police demanding the arrest of all the culprits and threatened to shut down Jorhat in the event of failure.
Several people have lost their lives in the past one year in India by lynch mobs after rumours of child lifting triggered via messages on WhatsApp.
According to reports, at least 20 people were killed in 14 separate incidents between May and July 2018 in various parts of India.
WhatsApp said it would fund research to find out why misinformation spreads on the platform like wildfire in India.
Two men were pulled out of their vehicle at Panjuri in Karbi Anglong district and beaten to death by a mob which believed they were child-lifters following dissemination of fake news on social media.
The five arrested today were--Raikom Timung, Mensing Kro, Roben Mech, Bikram Hanse and Protap Kro.
Assam Chief Minister Sarbananda Sonowal has announced to conduct the trial of the lynching in a fast track court.
Among those arrested, included the man who allegedly fanned the rumour on social media that child lifters have entered Assam, Director General of Police Kuladhar Saikia told reporters.