GAZA, Nov 3 (Reuters) - An Israeli air strike in the southern Gaza town of Rafah on Friday killed four members of a Palestinian police force headed by Hamas, said a source in the militant group, which leads the government. The source said the four were inside a jeep at the time of the strike. There was no immediate comment from the Israeli army, which has been engaged in a massive offensive against militants in the Gaza Strip, launched after gunmen from the territory abducted an Israeli soldier inside the Jewish state in June.