A blurry video clip posted on YouTube may show a gunman killing protesters in Tehran Monday evening.
In the clip, likely shot from a cell phone, a blue-shirted gunman fires an AK-47 into a courtyard from a second-story window.
In the foreground, a crowd of protesters shouts slogans as dozens of shots ring out. The gunman and his targets are behind a high wall, so the crowd doesn't move.
The footage broadly matches an incident that took place Monday evening in Tehran, as young protesters broke into a compound used by the Basij paramilitary force. Seven were reported killed as Basij members fired upon them.
"Marg bar Basiji" — "Death to Basij members" — reads a comment attached to the video clip.
The Basij, or "Mobilization," were founded by Ayatollah Ruhollah Khomeini in late 1979 to militarize women and men who were either too old or too young to serve in the regular military. Teenaged Basiji sacrificed themselves by walking into minefields ahead of tanks during the 1980-88 Iran-Iraq War.
After the war, the Basij was opened up to men of all ages, though recruitment took place mainly among the urban and rural poor. They became the frontline of enforcement of authority and were notorious for cracking down on protesters during a wave of student dissent in the late 1990s.
Since hardline President Mahmoud Ahmadinejad took office in 2005, the Basij has grown in numbers and influence, and it is directly controlled by the Revolutionary Guards, Iran's ideologically pure parallel military.