Two people were killed and seven injured after a bridge collapsed at an expressway construction site in South Korea, authorities have said.

Local media aired dramatic footage on Tuesday of what appeared to be a section of the bridge collapsing, sending a massive cloud of smoke into the air.

Two people died, six were seriously injured, and one suffered a minor injury, according to a statement from the National Fire Agency.

Authorities are still searching for one person, the agency said.

The incident took place at around 9:50 am, around 65 kilometres south of the South Korean capital.

Acting President Choi Sang-mok has issued urgent directives to mobilise all available resources and personnel for the rescue operation.

According to data from Seoul's Labour Ministry, more than 8,000 work-related deaths occurred in the country from 2020 to 2023.