A Hartford firefighter who lost his life battling a house fire in October died because his tank ran out of air, the Connecticut medical examiner’s office said. The medical examiner Thursday ruled the death of Kevin Bell an accident. Bell, 48, was a six-year veteran of the department and the first Hartford firefighter to die in the line of duty in 40 years. The Hartford Courant reported that an inspection of his engine company’s equipment before the deadly fire found safety issues including empty air tanks. The breathing apparatus that Bell was wearing has been sent to its manufacturer for testing.