DHAKA, Bangladesh — A fire at a garment factory north of Dhaka, the capital, killed at least 20 people and injured dozens on Tuesday, in the latest blow to the country’s largest industry.

The fire at a 10-story factory in the Ashulia industrial area, about 16 miles from the capital, started on the ninth floor around lunchtime, when most of the workers were outside. Local reporters who had canvassed hospitals said at least 24 people had been killed. Factory officials said they knew of about 20 deaths.

About 5,000 people worked in the building, producing pants for customers in the United States and Europe, said Delwar Hussain, a deputy managing director at the Ha-Meem Group, which owns the factory. Fire officials were still fighting the fire, which spread to the top floor, into the evening as people gathered at the compound to look for relatives.

It was not immediately clear which Western retailers were supplied by the factory. Garment factories employ about three million Bangladeshis, most of them women, to make clothes for stores like Wal-Mart and H & M.

Just days ago, three people were killed in labor protests. Workers have said they were protesting because some factories had not carried out a government-mandated 80 percent increase in the minimum wage, to 3,000 taka a month or about $43.

It was unclear what had caused the fire at the Ha-Meem factory and whether it was related to the labor unrest. Mr. Hussain said that the company suspected an electrical short circuit, but that investigators from the government and the garment industry association were still working to establish the cause.

Piles of clothes in garment factories are easily combustible. Fires can be very deadly because some factory owners lock exits to prevent workers from leaving their machines. Mr. Hussain said the doors at the company’s factory had not been locked.

International labor groups have criticized the safety of Bangladesh’s garment factories. A factory fire outside Dhaka in February killed more than 20 people.

The Bangladesh Garment Manufacturers and Exporters Association said it would pay the families of workers killed in the Ha-Meem fire 100,000 taka (about $1,400), and the company has promised to pay another 100,000 taka.

Mr. Hussain said the company hoped to reopen the first eight floors of the factory as early as Tuesday because they did not appear to be damaged. He said the company expected to meet all pending orders. The ninth floor was used as a finishing area where workers prepared shipments, and the 10th floor housed a dining hall, he said.