Supporters of a powerful political party in Pakistan's southern city of Karachi fired shots at the office of a television channel on Monday before ransacking the building, police said.
The protesters belonged to the Muttahida Qaumi Movement (MQM), senior superintendent of police Saqib Ismail said. Media reported they were angry about a lack of coverage of a hunger strike.
"MQM workers fired shots at the ARY (News) office, ransacked the premises and set fire to a police mobile," he said.
Local media said the protesters had rushed to the office of ARY shortly after the MQM leader Altaf Hussain, who lives in exile in London, had criticised Pakistan's media in a telephone address for failing to report on his workers' hunger strikes.
Security forces later arrived and dispersed the crowds. Local media said several people were wounded in the clashes.
The MQM protesters had earlier gathered outside the nearby press club where some had been on hunger strike to protest against alleged attacks by security forces on their members in Pakistan's violent commercial hub.
The MQM has held sway over Karachi for years and law enforcement agencies, its opponents and many residents have accused it of racketeering, abduction, torture and murder in its bid to maintain power. The party denies links to crime.