Many residents in Da Nang felt nauseous, dizzy and itchy on Sunday after inhaling toxic gas emitted from a scrap store.
The gas leaked into the neighborhood after Nguyen Van Son, 40, drilled a hole into a one meter tall metal container to sell the metal scrap to recyclers.
Son said he didn't remember the license plate number of the truck that sold it to him.
The vessel leaked what investigators believe was chloride gas into the area. Chloride gas is a volatile material that can cause death in people who inhale a lot of it. The vessel might have been around 30 years old, authorities said, Nhan Dan (People) newspaper reported Monday.
Military forces in the area stopped the gas leak the following day and brought the container away for further investigation.
Local residents said that Son began renting his storefront around a month ago and bought the 70-kg vessel several days ago.
The gas has caused vomiting and headache to more than 30 local residents, including 10 children.
Tran Thi Ut, 43, lives next to the store and remembers hearing a very powerful hissing emenate from the store before a column of orange-yellow smoke began pouring out of its windows and doorways.
"I felt like vomiting and my head was dizzy when smelling the gas. It only felt better when I washed my face with clean water," Ut said.
She and her family have since moved to an acquaintance's house far away.
Another local resident named Nguyen Hung had to rush his children, one seven years old and the other five, to hospital after they inhaled the gas.
"At first, I thought the problem was small but both of them kept vomiting, feeling dizzy and fatigue," Hung said.
Residents living hundreds of meters from the store also said they smelled the gas.