Two men and a woman stormed a government office in central Madrid, shooting and killing a policeman and wounded three other people, police said. The assailants took the policeman’s gun as he stood guard outside the ground-floor office, then used it to shoot the officer twice in the head, Spanish National Radio reported. One of the attackers fired at a second policeman and a man and a woman, none of whom was seriously injured. The assailants then fled on foot, police said. There was no immediate claim of responsibility for the first terrorist assault in the Spanish capital in 17 months.