"We were truly surprised to find out that it was boys of such a young age involved in these crimes. We've never seen offenders this young in these types of offenses," Conny Kjellberg of the Uppsala Police told the Upsala Nya Tidning.
The youths -- an 11-year-old, two 13-year-olds and a 14-year-old -- have committed at least three burglaries in December and January, The Local reported.
Police told the Nya Tidning the suspects are too young to be charged, but all four boys have been questioned, along with four other people, in connection with the crimes.
Some of the boys reportedly knocked on front doors of houses where lights were off and if nobody answered, other boys smashed through back windows.
A 25-year-old man also has been arrested on suspicion of receiving stolen goods, police said.
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