SEOUL, Oct. 25 (Xinhua) -- Two people were killed and two others were injured after collapsing from suffocation at a sewage purifier in southeastern South Korea, Yonhap news agency said Saturday.

Four workers passed out from asphyxiation around 11:31 a.m. local time (0231 GMT) at the sewage purifier, installed in the basement of a zinc processing company in Gyeongju, some 330 km southeast of the capital Seoul.

Two of the workers died after being transferred to a hospital, while the other two were in critical condition.

A separate worker outside the sewage purifier found the victims lying on the ground.

Before collapsing, the victims were believed to have worked on the plumbing. ■