POCHEON -- One person suffered cardiac arrest and three others were seriously injured after more than 40 cars were involved in a pile-up on an expressway in the northern city of Pocheon Sunday, officials said.

The multi-vehicle crash occurred at around 9:15 p.m. on the Guri-Pocheon Expressway in Pocheon, 46 kilometers northeast of Seoul, and the four were taken to nearby hospitals, according to the officials.

Around 21 others sustained minor injuries and have received treatment, they added.

The fire authorities issued an emergency response mode to handle the situation, and mobilized some 130 officials and dozens of vehicles and equipment for rescue and other necessary work.

The exact cause of the accident is not yet known, but the authorities said an icy road could have been a factor.