One worker was in cardiac arrest and two others were injured with authorities having rescued all seven workers trapped after a steel bar collapsed at an underground construction site in Seoul on Thursday, officials said. The accident was reported at 1:22 p.m. at the Sinansan Line construction site of Yeouido Station in western Seoul, leaving the seven workers trapped, according to police and rescue officials. A man in his 50s was found in a state of cardiac arrest and taken to a nearby hospital, while another 50-something male worker was moved to a hospital for a minor ankle injury. A foreign worker in his 30s came out of the site on his own and received treatment for minor scrapes on his wrist. The remaining workers evacuated to a vertical shaft before being rescued by firefighters. The accident is presumed to have occurred some 70 meters underground when a steel bar collapsed as concrete was being poured. Police plan to investigate whether safety measures were properly taken at the site.