"They have cut off the electricity to the street lamps on the Enghelab St. from Imam Hossein Sq. to Azadi Sq. and they are beating people in darkness. People have started fires to combat the tear gas," - an eye-witness to the BBC in Tehran.
The video is from Mehdi Saharkiz's Twitter feed today.
(The quote is the one timed 17.15. As always, help in translating Farsi is always appreciated.)