Two sky divers were killed in an accident near the Cape Cod Airfield on Sunday evening, Barnstable police said. The sky divers, who were jumping in tandem, landed on Race Lane in Marstons Mills, beyond the intended landing area at the airport, said Captain Sean Greene of the Centerville-Osterville, Marstons Mills Fire Department. The sky divers crashed around 5:20 p.m., according Barnstable police Sergeant David Myett. “It is very sad,” Myett said by telephone. “But we don’t have many details.” Barnstable police did not disclose the names of the sky divers. Myett referred all questions to the Cape and Islands district attorney’s office, which will investigate the deaths. Myett said he did not know the name of the company the pair was diving with, or whether there was an equipment malfunction. It was the second deadly sky-diving accident in the state in the past two months. Daniel Pelrine, a 37-year-old Mattapan ironworker, died on Aug. 17 in an accident in Pepperell.