Rescue efforts are underway for two workers believed to be trapped after a collapse at a construction site for the Sinansan subway line in Gwangmyeong, Gyeonggi Province. 

According to the fire agency and police, the collapse of a road at the construction site in Gwangmyeong's Iljik area was reported at around 3:13 p.m. on Friday. 

One of the two workers, an excavator engineer, is reportedly in communication with fire authorities via his mobile phone.

Another worker employed by POSCO E&C reportedly has yet to be reached.

The fire agency has dispatched 21 rescue vehicles, drones and 60 personnel under a Level One response alert issued at 3:50 p.m.

At around 12:30 a.m. on Friday, a report was filed about cracks in multiple central pillars supporting the underground tunnel at the construction site, prompting authorities to close surrounding roads for inspection and reinforcement work.

The city of Gwangmyeong issued a disaster alert, urging nearby residents to evacuate and drivers to take alternate routes amid concerns of another collapse near Yangji Intersection.