"The opposition Kaleme website said security forces and "people in civilian clothes" tried to disperse the crowd."
"The unrest came a day after websites close to opposition leaders Mir Hossein Moussavi and Mehdi Karroubi said they had been jailed."
"On Monday one of Mr Karroubi's sons told the BBC Persian service he had been told his father had been "taken by security forces to an unspecified location"."
This is going to lead to greater unrest. People say: "Capture a leader, capture an army." Never in a revolution would this work.
Also, about that tear gas, I hope the U.S. took the label off this time, or at least put a China one on.
Source