MARGARET WARNER: And now we turn to the confrontation in Iran.
The regime struck at its opposition again today, on the heels of yesterday's widespread bloodshed.
At least seven leading reform activists were rounded up today in Iran. State-sponsored press TV made the announcement.
IRANIAN NEWS ANCHOR: Reports say several political figures have been arrested over Sunday's unrest in Iran. Among those arrested are secretary-general of the freedom movement of Iran Ebrahim Yazdi, and Ghorban Behzadian Nejad, a senior aide to defeated presidential candidate Mir Hossein Mousavi.
MARGARET WARNER: State TV also reported, eight people were killed in Sunday's violence and another 300 to 500 detained. The opposition said police had opened fire on demonstrators. Confirmation was impossible due to government curbs on independent and foreign media.
But much of the mayhem was recorded on mobile phones and disseminated via the Internet, despite Iranian government efforts to block the transmissions.
This YouTube video shows demonstrators clashing in the streets of Tehran with police and the Basij, an irregular militia run by the Revolutionary Guard.
Another video purported to show a member of the Basij surrendering to protesters. Others showed a police station burning and demonstrators torching police motorcycles.
All in all, it was the worst violence since a disputed election returned Ahmadinejad to the presidency last June. Among those killed yesterday was the nephew of Mir Hossein Mousavi, Ahmadinejad's leading challenger in the election.
Ali Mousavi was allegedly run over by an SUV and then shot. His body was taken to a Tehran hospital, but it disappeared overnight. His family said the government removed it to preclude a funeral, which might spark more protests.
The protests were not confined to Tehran. Unconfirmed reports said four died in Tabriz. Fierce clashes also reportedly broke out in Isfahan, Najafabad, Shiraz, and elsewhere.
The protests coincided with the Shiite-Muslim holy day Ashura, honoring the martyrdom of Imam Hussein, a grandson of the Prophet Mohammed.
Mousavi didn't speak out today, but the other leading opposition candidate, Mehdi Karrubi, did. He fiercely criticized the crackdown on a religious holiday, writing on his Web site, "How is it that a regime is now sending bunches of thugs to the streets and shedding people's blood on the day of Ashura?"
The crackdown also brought widespread international condemnation.
President Obama spoke today.
U.S. PRESIDENT BARACK OBAMA: What's taking place within Iran is not about the United States or any other country. It's about the Iranian people and their aspirations for justice and a better life for themselves. And the decision of Iran's leaders to govern through fear and tyranny will not succeed in making those aspirations go away.
MARGARET WARNER: There were scattered reports of new trouble today. An opposition Web site said police fired tear gas to disperse Mousavi supporters outside a hospital in Tehran.