This post by Babak Dehghanpisheh is published by The Washington Post. Here is an excerpt: 

The protesters formed small groups. Some chanted “Death to the dictator,” a common rallying cry against Ayatollah Ali Khamenei, the country’s supreme leader.

Security forces, mostly plainclothes agents, had set up positions around the building and vans were parked nearby to transport detainees. Then, without warning, riot police on motorcycles began shooting metal pellets at the crowd, two witnesses told The Washington Post.

“They were shooting with guns, nonstop, everyone started running,” said a doctor who provided a written account of the attack.

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