LAS VEGAS (AP) -- A construction worker was killed in a tunnel at Lake Mead after some material became loose and building pressure sent grout flying through the air.
Another worker was injured during the Monday afternoon accident near Lake Mead National Recreation Area.
A spokeswoman for the Southern Nevada Water Authority says the condition of the second worker is unknown.
The two workers were alone in a segment of the 3-foot diameter tunnel when they were hit by the exploding grout material.
Workers completing construction in other areas of the tunnel were not affected.
The tunnel is part of a troubled effort to drill a third drinking water supply line to the Lake Mead reservoir. The project has been beset by flooding and cave-ins since construction began in 2009.