HAVANA: Cuba’s coast guard shot dead four people and injured six others traveling in a US-registered speedboat in an exchange of fire off the Cuban shore on Wednesday, the interior ministry in Havana said. The confrontation comes amid heightened tensions between the United States and communist Cuba, which lies just 100 miles (160 kilometers) across the Florida Straits. Cuba did not reveal the nationalities of the passengers aboard the US boat, and US officials made no immediate comment on the incident.