All the four accused were arrested.
A home guard jawan was also injured during the incident which took place last evening.
Constable Vinod Makwana stopped Karansinh Solanki who was riding a motorcycle and issued him a fine memo for brekaing traffic rules.
Solanki and his three friends, Vipul Solanki, Kirti Solanki and Akash Solanki, stabbed Makwana with knives in chest and stomach, the police said.
Kanji Thakor, a home guard jawan on traffic duty, tried to intervene, and was stabbed too.