Siddharth Maharia, son of Independent MLA Nandkishore Maharia, was driving the car at high speed at around 1.30 AM in C-scheme area here, police claimed.
He first hit an autorickshaw and then a PCR van, police said, adding under the impact of the crash, the three-wheeler fell about 200 feet away from the site.
"Two of the passengers of the autorickshaw died on the spot and as many were injured. One Assistant Sub Inspector and three other policemen on duty were also injured.
The ASI received head injury and is being treated while other policemen were given primary treatment, he said.
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Additional DCP Yogesh Goyal said the accused Siddharth was drunk, "as per the initial assessment", and a medical test was conducted to confirm it.
"There were four persons in the car. Two managed to escape and two -- Siddharth and his relative Jayant -- were caught. They are at a police station and action against the driver will be taken after the registration of an FIR," he said.
One of the deceased was identified as Jethamal (40) and efforts are on to ascertain the identity of others, SHO Ashok Nagar police station, Bala Ram said.
The autorickshaw was on its way from Chandpole to Mansarover when the mishap occurred.