POHANG -- Multiple fires broke out at steel plants of POSCO in the southeastern city of Pohang on Tuesday, residents and company officials said.

The fires began at around 7:30 a.m., they said.

"It is true that the fires broke out, and we are figuring out the current situation," a company official said.

Residents who witnessed the fires said there was a "loud noise and black smoke" at the POSCO plants.

There were no immediate reports of casualties.

President Yoon Suk-yeol has been briefed about the situation, his office said.

The cause of the fires was not immediately known, but the company is looking into whether the fires were related to Typhoon Hinnamnor, which moved out of South Korea early Tuesday morning.

POSCO has said it would suspend operations at the plants for about five hours early Tuesday as the typhoon was expected to hit the nation's southeast coast. (Yonhap)