According to Pakistan Today, "Saner elements in the National Assembly (NA) blocked the way of the Pakistan Muslim League-Nawaz (PML-N) and the Muttahida Qaumi Movement (MQM) parliamentarians on Tuesday as they tried to physically assault each other in fits of anger following the fiery speech of Opposition Leader Nisar Ali Khan, in which apart from verbally bashing the MQM, he demanded opening of a debate in the House on former Sindh home minister Dr Zulfiqar Mirza's allegations."
Wait, Khan's stepping to Mirza like that? We'll see how that turns out. In the meantime, if you want to skip ahead to parliamentary punches actually being thrown, they start at 1:44 and they're not even in Pakistan.