Gunmen in a car fired on a police checkpoint near the US Embassy in Yemen's capital on Monday, an Interior Ministry official said, hours after the embassy received threats of a possible attack. Police returned fire at two gunmen in the car, which fled the scene, the official said. It was unclear if anyone was injured. The official spoke on condition of anonymity because he is not allowed to speak to the press. He said three men in the area were detained. An attack on the embassy in September involving gunmen and explosives-packed vehicles killed 17 people, including six militants. Al-Qaida later claimed responsibility for that attack. A US Embassy spokesman could not be reached for comment on Monday night's shooting.