A fire at a shoe factory in southeastern China on Thursday caused “significant” casualties, according to China’s leader, Xi Jinping, who ordered officials to make every effort to investigate the cause of the blaze.

The fire broke out on Thursday at noon local time at the factory, which is in Jinjiang, a city in the Chinese province of Fujian. Video shown by Chinese state news media showed flames coming from the building’s top-floor windows and sending huge plumes of smoke over the complex. At least a dozen people appeared to be trapped on the roof as the factory was engulfed by flames and smoke.

Mr. Xi called on the local authorities to do everything they could to search for and rescue survivors, treat the injured, find the cause of the fire and “hold those responsible accountable,” according to China’s state broadcaster, CCTV.

China’s Ministry of Emergency Management said in a statement that the fire had “resulted in casualties” but did not give more details. The fire was mostly extinguished by 5 p.m., according to Beijing News.

According to CCTV, the factory belonged to the company Fujian Huiteng Shoes. The company’s business filings showed that it employed at least 155 people.