Screaming "Down with the Shah," 10,000 people, swept through the capital, carrying pictures of Khomeini. Though the whereabouts of the Shah was kept secret, rows of white-helmeted troops, backed by tanks, immediately sealed off access to royal palaces in the city and suburbs. In the heart of town green, they fired for 40 minutes. When the mobs entered government buildings, the troops opened up at point-blank range. The crowd fell back in confusion, regrouped, and raced down main avenues.