Beachgoers have been warned to stay alert after two shark attacks in as many hours left a trio of swimmers hospitalised with a range of injuries. Over just a four-mile stretch of coastline in Florida, the marine maulings left one woman having part of her arm amputated – while a pair of teen girls were left with multiple injuries, according to local emergency services. The first attack, at just after 1pm local time, saw a roughly 45-year-old woman attacked by a shark near WaterSound Beach in Florida’s Walton County. Fire officials said the victim sustained “critical injuries” to her lower left …