Hours after enraged MQM workers stormed the offices of media outlets on Monday, Rangers and police launched a major crackdown on the city’s largest political party.
At least one person was killed and several others were injured during violent clashes between protestors and police near Zainab Market.
Several vehicles were also torched by the demonstrators.
Tension began after MQM chief Altaf Hussain allegedly made a proactive speech, making anti-Pakistani slogans.
Veteran MQM leader Dr Farooq Sattar and opposition leader in the Sindh Assembly Khawaja Izhar ul Hassan were detained immediately after they reached the Karachi press club.
Dr Farooq Sattar pleaded the Rangers to allow him to brief the media, but he was barred and whisked away by the paramilitary force.
Irum Azeem Farooque, a female lawmaker of the MQM, said that she felt very embarrassed after watching videos of Mr Hussain and subsequent attacks on media houses.
MNA Sajid Ahmed was arrested from Malir area of the city.
Another senior leader Amir Khan was also taken into custody as he tried to leave Nine Zero, Karachi.