This is from the night of April 4th, 2012. That morning a 77 year old Greek man (Dimitris Christoulas) went into the Syntagma Park (right across from the Parliament building) and shot himself under a tree.
This is from the beginning of the protest that started at night. One the second flare is thrown, the police put on their gear and make their way down the stairs into the crowd.
BBC story about the events: youtu.be/olydoLFMJMA