Violence broke out after Mansoor Mukhtar, a local leader of the MQM, the governing party in Karachi, was killed [AFP]

Karachi has observed a day of mourning following the murder of a local leader of the city's governing Muttahida Qaumi Movement (MQM) party, and the deaths of several others in subsequent violence in Pakistan's business capital.

Eleven people were killed on Tuesday and dozens were injured following the murder of Mansoor Mukhtar.

The local MQM leader was attacked by gunmen in his house in a neighbourhood in the central part of the city early on Tuesday morning.

His brother and sister-in-law were also wounded in the attack. Mukhtar, and his brother Maqsood, later died in hospital.

Violence broke out hours later when unidentified men took to the streets burning vehicles.

A total of 35 vehicles were torched, the home minister of Sindh province, Manzoor Hussain Wassan, said.

Later, three people died in gunfire in different parts of the city.

Angry protesters reportedly also burnt tyres and unknown men forced shop owners to close down their business.

Aerial firing was also also reported in various areas.

"The city is closed because a worker of MQM has been killed. Obviously, the daily wagers are suffering from this
shutdown," said Saeed Ullah, a Karachi resident, on Tuesday.

Transport was suspended and most petrol stations were closed in fear of attacks and arson.

Street thugs

A city of more than 18 million, Karachi has a long history of violence, and ethnic, religious and sectarian disputes and political rows can often explode into battles engulfing entire neighbourhoods.

Street thugs and ethnic gangs have been used by political parties as foot soldiers in a turf war in a city which contributes about two-third of Pakistan's tax revenue and is home to ports, the stock exchange and central bank.

About 300 people were also killed last year - one of the deadliest years in almost two decades - in fighting linked
to ethnic and religious tensions that plague Karachi.

In one incident, 20 people were killed and dozens others injured in clashes between between armed activists of the MQM, and its breakaway faction, the Mohajir Qaumi Movement-Haqiqi (MQM-H).

According to the independent Human Rights Commission of Pakistan, more than 1,000 people were killed in ethnic and
politically linked violence in 2011.