New Delhi, Nov. 7 -- A 60-meter (196-foot) tower collapsed during demolition work at a decommissioned thermal power plant in the South Korean city of Ulsan, killing three people and leaving at least two others 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 pronounced dead, and a doctor at the site confirmed the death of another worker who was among three people in the rubbl...