Siddharth Maharia, son of Independent MLA Nandkishore Maharia, was driving the car at high speed around 1.30 AM in C-scheme area of the city, and was arrested under section 304 of IPC (punishment for culpable homicide not amounting to murder), police said.
The car first hit the autorickshaw and then the PCR van, police said, adding the impact of the crash was such that the three-wheeler fell about 200 feet away from the site.
"The five injured were rushed to SMS hospital where another passenger of the autorickshaw succumbed to injuries," Jaipur Deputy Commissioner of Police, South, Manish Agarwal said.
The ASI received head injury and is being treated, while other policemen were given primary treatment, he said.
The DCP said the accused was placed under arrest today.
Additional DCP Yogesh Goyal said "as per the initial assessment", the accused was drunk and a medical test was conducted to confirm it.
Meanwhile, Siddharth claimed that he was not driving the car. He also denied consuming alcohol.
Two of the deceased were identified as Jethamal and Kailash, both aged around 40 years, and efforts were on to ascertain the identity of the third deceased, SHO, Ashok Nagar police station, Bala Ram said.
The autorickshaw was on its way from Chandpole to Mansarover when the incident occurred.
