A 6-year-old boy was dragged to death when two men stole his mother's car and he got stuck in the seat belt trying to escape, police said Thursday.

Joao Helio Fernandes was in the car with his mother and his sister Wednesday night when approached by the thieves in Osvaldo Cruz, a district on Rio's poor north side, police said.

The women managed to escape and Joao opened the door but was unable to unbuckle his seat belt and was dragged for about 4 miles, police inspector Hercules Pires do Nascimento of the 30th precinct station in the Marechal Hermes district said by telephone.

The thieves saw the boy was stuck in the belt and drove at high speed, swerving back and forth, in an unsuccessful attempt to get him out of the car, Nascimento said.

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The thieves eventually abandoned the car and walked away, leaving the boy hanging from the car. He was taken to a hospital but died. No arrests have been made in the case.

"It's the first time anything like this has happened here," Nascimento said. "Usually this is a pretty quiet neighborhood."