Eyewitness reports vetted by reliable groups are now coming out of Iran, indicating that the government response specifically targeted opposition leaders to demoralize the protesters.Opposition leader Mehdi Karroubi was ambushed as he descended from his vehicle at Sadeghiyeh Square, his son Hossein said in an interview with Tehran Bureau, an independent Western news organization affiliated with PBS’s “Frontline” that reports extensively from Iran.

He said Karroubi was being treated for burns to his face and eyes after having been attacked repeatedly with pepper spray.

Hossein Karroubi also confirmed that another of Karroubi’s sons, Ali, had been arrested. He said the family didn’t know where he was being held or how he was being treated.

In addition to the arrest of Zahra Rahnavard, the wife of the main opposition leader, Mir Hossein Mousavi, which has been confirmed by Western news agencies, independent and opposition reports said Mohammad Reza Khatami, a brother of reformist former president Seyyed Mohammed Khatami, was arrested, the opposition Web site Jaras, or Green Road Network, claimed. A vehicle carrying Khatami himself was attacked, it said, without offering further details.
 

This video purports to show Karroubi’s supporters cheering his arrival in Arya Shahr before his arrest:

Mohammad Ashrafi, a leader of the anti-government labor movement, was arrested before dawn, his wife told the anti-government Iran News Agency.

Zahra Eshraghi, granddaughter of Ayatollah Ruhollah Khomeini, leader of the 1979 revolution, was arrested briefly, the opposition Web site Rahesabz said in a report that was eventually confirmed by Western agencies.

Numerous reports indicated that many further arrests were likely later today. This video, which NBC News hasn’t been able to verify,  claims to show of masses of riot police walking along the street, carrying paintball guns to tag protesters for arrest: 

“They broke the momentum,” a U.S. official told NBC News’ Robert Windrem. “This is a good day for the Revolutionary Guard, as well.”

Another U.S. official conceded that “it appears things have gone relatively well for the regime,” but he added, “The trick is that, while this solves the day, it does not solve the problem.”