KARACHI: Gunmen killed at least 37 people in Pakistan’s largest city after the assassination of a lawmaker, officials said Tuesday. Dozens of vehicles and shops were set on fire as security forces struggled to gain control of Karachi.

 The southern city of more than 16 million has a history of political, ethnic and religious violence, and has long been a hide-out for al-Qaida and Taliban militants. Its stability is important for Pakistan because it is the country’s main commercial hub.

 The latest unrest came after Raza Haider, a provincial lawmaker, was shot dead along with his bodyguard in a mosque in Nazimabad area while preparing to offer prayers Monday.

 Haider was a member of the Muttahida Qaumi Movement, the political party that runs the city and represents mainly descendants of migrants from India who settled in Pakistan when it was created in 1947.

 The MQM’s main nemesis is the Awami National Party, a secular nationalist party whose main power center is Pakistan’s northwest and whose base is the ethnic Pashtun community.

 Independent analysts say followers of all political parties in Karachi are heavily involved in criminal activities such as protection rackets and illegal land dealings. In certain neighborhoods, armed men linked to political parties stand guard at checkpoints.

 Officials from different hospitals put the total death toll by Tuesday morning at 37. Some 80 additional people had suffered gunshot wounds, they said. A furniture market was among the places set ablaze.

 Sindh province spokesman Jamil Soomro said at least 10 people were arrested, and police and Army Rangers were dispatched throughout the city to impose order. But gunfire could still be heard Tuesday morning, and fires were still being set in some areas.

 Schools and colleges in Karachi and other urban centers in the province were ordered to stay closed by the government Tuesday. Some officials blamed unspecified “invisible hands” for the violence.

 “It is very sad, and we believe that it is the work of those forces who want to destabilize the elected government,” Soomro said.