TOPEKA, Kan. (AP) _ Three construction workers died after being pulled from a 23-foot-deep manhole.

One man died at the scene Monday; two died at the hospital. Autopsies were scheduled to determine the cause of death.

``We have the potential for carbon monoxide. We have the potential for oxygen depletion,'' Fire Battalion Chief Greg Bailey said.

Authorities identified the victims as Norman Emerson, 64; Lawrence Saloga, 53; and Brian Phelps, 22.

The men were discovered in the concrete-lined manhole by a co-worker, who called 911.

The three were checking a sewer line for leaks in a new housing subdivision.

All were employees of Emerson Construction.

Norman Emerson founded the business nearly 40 years ago with his brother, said Todd Emerson, the victim's nephew.