Three workers were killed in an accident at a supermarket construction site near Florence, Italy, on Friday morning, according to authorities. Three more workers were injured, while two were considered missing as of Friday afternoon. The accident happened when a reinforced concrete beam toppled over a slab of a pre-fabricated building, which then collapsed. Local authorities said about 50 firefighters were still searching for the missing workers but feared the death toll of the incident could climb. According to the president of the Tuscany region, Eugenio Giani, there were about 50 workers on…