In the video, the attackers are seen aggressively confronting the men who the police say were tannery workers carrying animal hide. The incident took place in Gir Somnath, about 400 km from Ahmedabad.
"Where did you get the cow skin?" one of the attackers is heard demanding. After the third degree, they are seen tying the men to a car and thrashing them brutally with sticks on their naked back.
Early this morning, the group uploaded the video online, unwittingly helping the police track them down. Two of the accused are still missing.
A man who claims to be a member of the BJP's ally Shiv Sena alleged that the men were beaten for transporting beef illegally.
"We had information that a few people were slaughtering cows and eating beef. We have informed the police and they will investigate further," said Sena's Ramesh Goswami.
Attacks linked to beef-eating and alleged cow killing were at the centre of a debate last year on intolerance, with activists and opposition parties accusing the BJP-led central government of not reining in fringe elements.
In September, a Muslim man was lynched in Uttar Pradesh's Dadri over rumours that he had beef in his house. Amid outrage over the incident, "cow protection groups" became active in some states.
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