SEOUL, South Korea (AP) — A fire broke out at a resort construction site in the South Korean city of Busan on Friday, killing at least six people, fire officials said.

About 100 workers managed to evacuate the site, while another 14 were rescued by helicopter from the top of the structure, said Hong Moon-shik, chief of the Busan Gijang District Fire Department.

Hundreds of firefighters were deployed to the site and had largely extinguished the blaze by Friday afternoon, hours after it was reported at around 10:20 a.m.

Hong said six people were found unconscious on the first floor of the structure, near where the fire was believed to have started. All six were later pronounced dead at hospitals. At least other 25 people sustained minor injuries.

He said the cause of the fire wasn’t immediately clear.

Television footage showed gray-black smoke and flames rising from the site and a helicopter approaching the building as part of rescue efforts.

Shortly after the blaze was reported, the country’s acting president, Choi Sang-mok, instructed officials to deploy “all available personnel and equipment” to put out the fire.