"The rangers and police conducted joint operations in various parts of the city overnight," a Rangers spokesman said.

The police raids came amid mounting calls from leading business groups and politicians for the army to step in to end the spreading violence. But President Asif Ali Zardari rejected calls for military intervention in the ethnically-sensitive city.

Police arrested three cold-blooded killers who confessed before the media that they were killing innocent people in their “torture houses” in Karachi.

"We have conducted 82 different raids, big and small, all across the city since last night, and have arrested 72 people," Karachi police chief Saud Mirza said.

Mirza said the raids by police and paramilitary rangers would continue and had already shown results with only one person killed on Wednesday in the least violent day for a week.

Interior Minister Rehman Malik announced Wednesday that Rangers and police have recovered illegal weapons and drugs from 83 miscreants in Karachi.

Police and Rangers carried out joint search operations in different areas of Karachi after Tuesday midnight following a high-level meeting in Islamabad jointly chaired by Zardari and Prime Minister Yousuf Raza Gilani gave approval for police operations in troubled areas of the metropolitan city.

The Rangers and police are patrolling in different areas of the city while heavy contingents of Rangers and police have reached Orangi Town and Qasba Colony.

Rangers have also been deployed in Old Area Lyari, however, police will launch all operations in Qasba Colony.