A chemical leak at an LG Display factory in Paju, Gyeonggi Province on Wednesday has left at least seven workers injured.

Two workers were left critically injured after their hearts stopped, necessitating CPR. The other five suffered minor injuries.

The accident occurred when tetramethylammonium hydroxide(TMAH), a toxic substance used in the production of semiconductors, leaked on the fifth floor of the factory at 2:20 p.m., presumably as contract workers were connecting pipes.

Emergency workers brought the leak under control in about 25 minutes.

In a statement, LG Display apologized for the accident and pledged to do all it can so that the injured workers quickly recover.

It also promised to cooperate with authorities to determine the exact cause of the accident.