The local Katrineholms-Kuriren newspaper reported that the accident took place around 2pm on Friday. The ice cream truck slammed into the passer-by near the town Varbo on route 671.
"It appears a person jumped into the truck and took it when the ice cream man was standing outside," local police spokesman Pontus Bjuring Gerlich told the TT news agency.
In the get-away, the car thief then hit a person who was standing by the side of the road speaking with a friend.
Emergency services rushed to the scene, with Western Södermanland county police first telling TT that the victim had been seriously injured. The victim later died from the injuries.
A few kilometres away, the ice cream truck veered off the road before landing in field. Two witnesses to the incident then gave the rogue ice cream truck driver a ride back into Sköldinge.
"Those people people will be questioned by us," Urban Nordqvist of the police told TT.
No arrests have been made and the suspect is believed to have fled in a Mazda he stole shortly after returning to Sköldinge.
A police patrol later caught sight of a Mazda and gave chase.
"Police broke off their pursuit in central Flen due to high speeds. The stolen car then continued in the direction of Hälleforsnäs," Nordqvist said.
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