One of the men went into the manhole to seal the leak and was overcome by toxic fumes generated by the repair effort.

The Sheriff's Department reported: "This victim collapsed into water that was approximately chest deep. The second victim then went into the manhole in an attempt to rescue the first victim. This individual was also overcome and also collapsed."

The Sheriff's Department has not identified which of the two men was the first into the manhole.

Personnel from the Bear Lake Ambulance Service and Bear Lake Fire Department removed the men from the manhole but were not able to revive them, despite extensive efforts.

Both men were pronounced dead at Bear Lake Memorial Hospital in Montpelier.

The Sheriff's Department said the men were doing work as part of the Georgetown city sewer project.

Georgetown is a community of about 470 people located on Highway 30 between Montpelier and Soda Springs.