A Texas sewer line accident has killed one worker with another is still missing after they entered a sewer without wearing protective breathing equipment. The fatality is believed to have been caused by gas exposure, with emergency officials speculating that the other worker likely also died after being overwhelmed by noxious fumes.

The accident occurred last Thursday in Fairview, Texas, a small town located about 30 minutes north of Dallas.

After emergency workers discovered the first worker's body, they donned oxygen masks and protective clothing to begin searching for the missing man. A fire chief said his staff is optimistic, but admitted that the missing worker is most likely dead and may have been swept away from the other victim in a current.

Authorities believe the men were trying to replace a plug on a sewer line when they were exposed to the poisonous gas. The first victim entered the sewer to remove the original plug, but did not emerge. In response, the second man likely entered the sewer to find him. Witnesses say that neither worker was wearing a mask.

Another worker and brother of the deceased victim explained that the team had almost completed a yearlong project, with the replacement of the plug being one of their final tasks to complete.

Officials say that the urgency to finish the job likely contributed to the workers' failure to take appropriate safety steps. Although sewer workers generally check the quality of the air before entering a line, officials say there was probably not enough oxygen to support the workers. Officials said that they do not know if either worker conducted an air quality test before beginning the operation.

The Occupational Safety and Health Administration have launched an investigation regarding the fatal accident. The company that contracted the workers, which is based in Minnesota, has declined to comment on the incident.

The company could potentially face OSHA fines as well as personal injury lawsuits brought by the families of the workers if it is found to have put its workers at risk.

Source: ABC News, "Fatal Sewer Line Accident in North Texas," Jamie Stengle, Nov. 3, 2011.