Updated

South Korean officials say 20 patients and a nurse have died in a fire at a hospital in the southwestern city of Jangseong.

An officer with the Jangseong Fire Department says that most of the victims were elderly patients. The officer spoke on condition of anonymity because of office rules.

The officer says the victims died after suffocating on poisonous gas.

The officer says there were 33 patients and a nurse on duty when the fire broke out on the second floor of an annex of Hyosarang Hospital early Wednesday morning. Seven people were injured

The fire was put out after about seven minutes. The cause was not immediately known.

The fire comes as South Korean officials are still searching for missing passengers from a ferry sinking last month that killed or left missing more than 300 people. South Korea has also had two subway accidents in recent weeks.