A milk van overturned following which heavy vehicles rammed into each other on the Delhi-Jaipur national highway near Amber around 8 AM, they said.
In the mishap, 12 people were injured, who were rushed to the SMS hospital where the condition of three victims was said to be serious, they said.
Traffic was also halted for a brief period on the highway, before the police officials cleared the way.
Cold wave is prevailing in the desert state, where fog for the past few days has disrupted normal life. Rail and road traffic have been impacted due to the poor visibility.
People in the state experienced bone chilling cold as the icy winds swept the state since yesterday.
Mercury is expected to fall further in the next 24 hours in the state, a MeT forecast said.