Minnesota health officials have issued an urgent alert after an unvaccinated child with measles visited the Mall of America while contagious. The child, hailing from Dakota County, spent time at the mall’s theme park on May 24 from 5 pm to 9 pm. During this 4-hour period, thousands of visitors might have been exposed to this highly infectious viral illness.

Health authorities are particularly concerned because the source of the child’s infection is still unknown. Jessica Hancock-Allen, the director of Minnesota’s infectious disease division, described this situation as “worrying,” indicating a potential for community spread.