In the get-away, the car thief then hit a person who was standing speaking to a friend by the side of the road near the town of Varbo on route 671.
The ice cream truck had been stolen in Sköldinge, a few kilometres from the scene of the accident.
"A person is reported to have jumped in and taken the vehicle when the ice cream was outside," said Pontus Bjuring Gerlich at the Västra Sörmland emergency services.
Emergency services rushed to the scene and despite efforts to save the victim's life, they later died from their injuries.
A few kilometres away, the ice cream truck veered off the road before landing in a field. Two witnesses to the incident then gave the rogue ice cream truck driver a ride back into Sköldinge.
The man is suspected of having then stolen a new car, a Mazda. A police car spotted the stolen Mazda and gave chase.
"Because of the high speed police called off the chase in central Flen," said Urban Nordqvist at Sörmland county police to the TT news agency.
The arrested man is reported to be familiar to police.
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