Image Credit... The New York Times

On Wednesday evening the police raided the home of the owner of the Karachi factory, Abdul Aziz, who appeared to have gone into hiding. According to an online business information service, his company, Ali Enterprises, manufactured denim, knitted garments and hosiery and had capital of between $10 million and $50 million.

His nephew, Shahid Bhaila, the chief executive officer of the company, was also being sought for questioning. The police said both men had been placed on the exit control list, barring them from leaving the country.

The Muttahida Qaumi Movement, the most powerful political party in Karachi, announced three days of mourning. The city electricity company said it would cancel all outstanding bills for the families of those affected as a good will gesture.

The cause of the fire remained unclear. Geo News, the largest news channel, speculated that it had been started by extortionists, reporting that Mr. Aziz had previously faced a demand for a shakedown payment of more than $100,000, which he refused.

But others said an electrical fire was more likely. Wali Muhammad, a former electrical inspector, said that most accidental fires are caused by short circuits in equipment. But since 2003, he said, inspectors had been forbidden by law from visiting factories in Karachi and Punjab; it was not immediately clear why.