SEOUL, South Korea >> A fire that started Friday morning in a hospital emergency room in South Korea killed nearly 40 people, mainly from inhaling smoke, and injured dozens more in one of the country’s deadliest blazes in recent years.

Several injured are in critical condition and the toll is feared to increase, fire officials said.

Sejong Hospital in the southeastern city of Miryang had a total of 194 patients before the fire at its general medical ward and its nursing ward for the elderly. The blaze began at the general ward’s first-floor emergency room and most of the dead were from the first and second floors, the National Fire Agency official said.

The cause of the fire wasn’t immediately determined. Miryang fire officials put out the blaze at 10:26 a.m., nearly three hours after it started and preventing it from reaching the upper floors. The hospital’s operations were suspended after the fire.

Most of the 39 deaths appeared to be due to suffocation, with only one suffering burns, said an agency official who spoke on condition of anonymity because he wasn’t authorized to speak to media.

The identification of the dead was underway, he said.

Agency official earlier said many of the deaths were confirmed after the victims were taken to other hospitals while being put on artificial ventilators.

President Moon Jae-in convened an emergency meeting with senior advisers and expressed regret over the blaze. He ordered officials to provide necessary medical supports to those rescued, find the exact cause of the fire and work out measures to prevent future fires, according to his spokesman Park Su-hyun.

South Korea is one of the fastest-aging countries in the world and has many nursing hospitals, which are preferred for elderly people who need long-term doctors’ care.

Several recent fires in South Korea have been deadly.

In late December, 29 people were killed in a building fire in central Seoul, which was the country’s deadliest blaze over the past decade before the hospital fire. Last weekend, a fire at a Seoul motel killed six people, and police arrested a man who allegedly set it ablaze in anger because he had been denied a room for being heavily drunk.

In 2014, a fire set by an 81-year-old dementia patient killed 21 at another hospital for the elderly.