I went to Costa Rica in 2014 with wife and daughter. Brief research for the trip clearly described the dangers of road bandits, and the most dangerous areas. Limon was at the top of the list.
There was one news story, from 2007, where 3 armed bandits attacked a tour bus near Limon carrying US tourists from a Carnival cruise ship. The Americans were "senior citizens", and included a reunion group of US Marine Viet Nam vets. In short order, one bandit was dead with a broken neck and the other two had fled.