RNA - Alwar police chief said the suspects were detained late Wednesday after examining video footage shot by onlookers.
"We saw the videos and identified at least five people who were at the spot. We called those five people to the police station and found that three of them were directly involved in assault on the victims," Rahul Prakash said on Thursday.
Police earlier listed more than 200 people as suspects in the murder case and posted a reward to help identify the attackers.
Prakash said police were still trying to identify most of the 200 vigilantes.
The official noted that police had also arrested 11 survivors of the attack, adding they had been charged under various sections of Rajasthan's cow protection law.
Police said on Wednesday that Pehlu Khan, 55, died in hospital two days after a group attacked his cattle truck on a road in the region.
The Muslim was driving in a convoy of six cattle transport trucks when the mob intercepted his vehicle. A video of the attack was broadcast on Indian television, showing the man being beaten with sticks and iron rods.
The death sparked fury Thursday in India's upper house of parliament, where opposition lawmakers shouted slogans against Prime Minister Narendra Modi's government.
Reacting to the murder, Rahul Gandhi, vice president of the opposition Congress party, said in a Twitter message that there had been a "shocking" breakdown of law and order. "When government abdicates responsibility and allows lynch mobs to rule, tragedies of immense proportion follow."
This is the latest assault in a spate of mob killings in the name of the revered animal in India.
Gangs of “cow protectors” have been implicated in killing at least 10 people in the past two years.
Police are regularly accused of working alongside cow-protection vigilantes.
India's history is pockmarked by horrific Hindu-Muslim communal clashes in the past. Several incidents of violence against Muslims and other minority groups have fueled concerns as religious intolerance is growing under the Hindu nationalist government.
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