SEOUL, South Korea — A 60-196-foot tower collapsed during demolition work at a decommissioned thermal power plant in the South Korean city of Ulsan, killing at least one person and leaving four presumed dead, officials said Friday.

Five people remain trapped under the rubble, including two whom officials have yet to locate.

Nine people were working at the site when the boiler tower collapsed Thursday afternoon. Rescue workers pulled two to safety shortly after responding, but another worker rescued later was pronounced dead at a hospital early Friday.

Hours later, they pulled out another worker who was presumed dead and confirmed the location of three others, also believed to be dead, said Kim Jeong-shik, an official with Ulsan’s fire department.

The search was temporarily halted Friday morning due to concerns over unstable rubble, and officials postponed planned stabilization work before resuming the search after spotting additional workers.

— The Associated Press