An 11-year-old boy managed to hack into a replica of Florida's election results website in 10 minutes during a hackers convention and change names and tallies, organizers said, stoking concerns about security ahead of nationwide votes.

The boy was the quickest of 35 children, ages 6 to 17, who all eventually hacked into copies of the websites of six swing states during the three-day Def Con security convention held last weekend, event organizers said on Twitter this week.

The event during one of the world's largest security conventions was meant to test the strength of U.S. election infrastructure and details of the vulnerabilities would be passed on to the states, it added.