Three suicide bombers suspected of planning an attack on a "high-profile" target in Pakistan's southern port city blew themselves up after police surrounded the house they were hiding in.
The suicide bombers linked to an outlawed militant outfit with close links to al-Qaeda, detonated themselves as security forces tried to flush them out from a building in the shanty Baldia town on the city outskirts, police said.
The raid on the militant outfit came as Pakistan Prime Minister Yousuf Raza Gilani reached the metropolis on an official visit.
There was no immediate suggestion that the men were targeting Gilani, whose motorcade was recently attacked near the capital.
Police also recovered the body of a prominent city transporter Shaukat Afridi, who was a supplier of fuel and goods to the US and NATO forces in Afghanistan.
The Pashtun transporter was reported to have been kidnapped on May 8 from the posh locality of Clifton and was being held for ransom.
Police made a huge haul of 10 kg of explosives, two suicide jackets, seven pistols and nine hand grenades from the Karachi house which was badly damaged by the explosion.
Police were tipped off about the presence of the Lashkar-e-Jhangvi militant by a leader of the outfit who had been nabbed earlier.
Initially, the militants resisted the police siege and lobbed at least five grenades at the police, but caused no casualties.
"The militants blew themselves up after their ammunition was exhausted," police said.
They said four bodies were recovered from the debris of the house, which was destroyed in the blast.
Karachi, Pakistan's commercial capital is considered a militant hub and has witnessed large scale political and religious violence and the raid in the city signalled that Pakistani armed forces were spreading their dragnet to encompass southern part of the country as well.
Lashkar-e-Jhangvi is one of the most feared militant outfit and is often associated with sectarian attacks and suicide bombings on mosques. Its fighters were trained in camps in Afghanistan and have joined terror attacks sanctioned by Al Qaeda.
Bodies of the slain militants were recognisable and police said that they were wanted over the killings of several local leaders and clerics from the minority Shiite sect.
"We have saved Karachi from death and destruction. We know who they were and what was their target in Karachi, but we cannot disclose it immediately," police said.