Over the past four days, a wave of ethnic violence has killed at least 95 people in Karachi, paralyzing Pakistan's largest city. Some roads are deserted, shopping malls and markets are shuttered.

Masked militants used Molotov cocktails and rockets, attacked public passenger buses and burned down houses, killing 25 people on Friday alone, mostly in hit-and-run terror attacks in ethnically mixed districts of the city, says police and residents.

With shoot-on-sight orders, paramilitary forces and police have intensified patrols in troubled neighborhoods in an effort to quell the city's deadliest episode of ethnic violence.

At the center of the bloodshed are districts of Orangi and Qasba Colony, considered to be among the biggest slums in South Asia, with mixed population of Pashtuns and Mohajirs. The labyrinthine alleys of these poor neighborhoods are edged with hillocks where militants armed with automatic weapons and rockets have taken up positions.

“We are besieged with no rations, no water for three days,” says a resident, Abida Khatoon. “We feel like moving targets as there is intense firing from every direction."

While Mohajir and Pashtun ethnic parties have not traded accusations over the fresh round of violence, tensions between the two groups have recently flared.

The decades-old rivalry between Muttahida Qaumi Movement (MQM) party, which represents Urdu-speaking Mohajirs, and Awami National Party (ANP), a party for Pashtuns, has intensified with an influx of Pushto-speaking people to Karachi from the troubled Khyber Pakhtun Khawa province and tribal belt along the Afghanistan border.

Still, both parties have refrained from pointing fingers this week. Most of the blame seems vaguely hoisted on "terrorists" or the Pakistani Taliban.

“The extremists are targeting both innocent Mohajir and Pashtun population,” says Wasey Jalil, central leader of MQM. “They want to destabilize Karachi to create anarchy in Pakistan.”

“But we will not let them [extremists] succeed," he says.

Another prominent MQM leader, Haider Abbas Rizvi, called the violence a conspiracy to divide Karachi by linguistic and ethnic differences, blaming the attacks on the Pakistani Taliban.

“We have been saying that for years that there is Talibanization going on. The [Taliban] are strong in Karachi. There are thousands of madrasas here, and Taliban leaders like Mullah Baradar were caught here. We need to eliminate them before they gather further strength in Karachi, which is (the) jugular of Pakistan,” says Mr. Rizvi.

Meanwhile, ANP central leader, Shahi Syed, demanded the government to carry out investigations into the killings of 25 members of his community and of other innocent victims.

Federal Interior Minister, Rehman Malik, announced that a targeted operation would be launched soon against the “terrorists” without any discrimination, adding that 89 suspects have already been picked up by security forces.

“We have collected information through satellite images about the hideouts of terrorists,” says Mr. Malik, while admitting “there are Taliban here in Karachi.”

The situation remains tense in Karachi. The MQM observed a day of mourning Friday, resulting in a lost work day in the country's commercial hub, jolting the fragile economy.

"If the bloodshed in Karachi continues, it will hurt the government badly because it will intensify the domestic political pressure," says Prof. Tauseef Ahmed. "And the government is already struggling to bring the weak economy back on track and bogged down with pressure from Washington to step up its fight against Al Qaeda and Taliban militants along Afghanistan border."