LAX terminal evacuated after carbon dioxide leak

(CNN/ KYMA, KECY) - Four airport workers were hurt in an apparent gas leak at Los Angeles International Airport Monday.

Fire officials say a woman and three men were working in or near a utility room when a popping sound was heard, and there was an apparent release of carbon dioxide vapor.

The condition of the most severely sickened person has been upgraded from grave to critical.

Hazardous materials experts closely examined the area with sophisticated instruments and found only a trace residue of carbon dioxide remaining in the utility room.

Fans are being used to further ventilate the area.

The incident happened in terminal eight near the baggage area.

The terminal was cleared of passengers but has since been reopened.

A federal aviation administration ground stop for arriving united airlines was also lifted.