Several thousand people have demonstrated outside the former U.S. Embassy in Tehran to mark the 35th anniversary of its takeover on November 4, 1979. Participants in the annual demonstration burned American, Israeli, and British flags and chanted slogans against the three countries. In January 1979, under mounting pressure from street protests and anger at his brutal reign, Iran's Shah Reza Pahlavi fled the, leading to the overthrow of the royal regime by guerrillas and rebel troops the following month. Eight months later, and after much turmoil, led by hundreds of students later known as the Muslim Student Followers of the Imam's Line, radicals broke into the U.S. Embassy in Tehran on November 4, 1979, and took 90 people hostage in a standoff that was to last more than 14 months. The leader of the revolution, Ayatollah Ruhollah Khomeini, returned to Iran from exile and became supreme leader of the Islamic Republic of Iran in December 1979.