DHAKA, Bangladesh — At least 51 people died in a fire on Thursday evening at an industrial building outside the Bangladeshi capital, Dhaka, the latest disaster in a country with a long history of unsafe working conditions in its factories.

       The authorities warned that the death toll could rise as firefighters continued to sift through the wreckage. At least 200 people were working in the building when the fire broke out, the police said.

       The fire, at a seven-story building where fruit drinks and plastic packaging were made, burned for nearly 24 hours, filling the air with thick plumes of black smoke, until it was extinguished on Friday afternoon.

       “We have worked so hard to control the fire,” said Dinmoni Sharma, the deputy director of the fire department in Dhaka. “Many are still missing, and we fear that there are more dead bodies. We are still working to recover them.”

       It is unknown what the conditions were like inside the building, but some of Bangladesh’s biggest past disasters took place in factories where doors were chained shut to keep workers from slipping away.

       Two people inside the building, in the district of Narayanganj, about 10 miles southeast of Dhaka, leapt to their deaths trying to escape the fire, officials said. Emergency workers recovered 49 additional bodies, and at least 25 people were rescued, most of them with injuries.

       The police were preparing to file a case against the building’s owner, Hashem Food Limited, a division of the Sajeeb Corporation, a large Bangladeshi packaged foods conglomerate, according to the police superintendent, Jayedul Alam.

       Mr. Sharma said that many missing-person reports had been filed by relatives of the factory workers, hundreds of whom gathered in front of the building overnight. Some, clutching photographs of missing relatives, protested, while others vandalized nearby shops and cars as they awaited for news of their loved ones. The police used tear gas to disperse the crowds, local media reported.

       People continued to wait for news outside the building late Friday as firefighters searched the upper floors.

       Some of the recovered bodies were so badly burned that identification will only be possible by DNA testing, said Gen. Sazzad Hossain, the director-general of the Bangladesh Fire Service and Civil Defense.

       The district magistrate, Mostain Billah, said that an inquiry would try to determine the cause of the fire. Officials said they suspected that it started in a ground-floor storage area.

       Deadly fires have plagued Bangladeshi factories, especially those in its garment industry, which accounts for about 80 percent of the country’s exports.

       A large fire at the Tazreen Fashions factory killed 112 people in November 2012. Iron grills covered the factory windows, and the gate was locked. The next April, the collapse of the Rana Plaza building killed 1,134 people in the garment industry’s biggest disaster in Bangladesh.

       After the Rana Plaza disaster, labor and safety standards improved in thousands of factories, with fire alarm and sprinkler systems installed and organized workforces securing slightly better working conditions and pay.

       However, despite a public outcry after the tragedies, conditions in many factories have remained largely unchanged, and fires are common. The International Labor Organization said in a 2017 report that Bangladesh’s regulatory framework and inspections “had not been able to keep pace with the development of the industry.”

       Between 2012 and 2019, there were more than 150 fire and other safety episodes connected to the country’s garment industry, according to the Solidarity Center, a workers’ rights organization.

       A total of more than 1,300 people died in those incidents, and more than 3,800 people were injured.

       Saif Hasnat reported from Dhaka, Bangladesh, and Emily Schmall from New Delhi.