HANGZHOU -- Five people have died after inhaling excessive amounts of carbon monoxide in a reservoir tunnel in east China's Zhejiang Province, sources with the local government said Wednesday.

The accident happened around 6:00 p.m. Monday in Wugen Town, Wenling City, when five people, including three managers of the Kengpan reservoir and two electricians, were checking pipes in a tunnel.

Local residents had complained about insufficient water supplies and asked them to replace the pipes with bigger ones, a local resident said.

Their bodies were discovered Tuesday morning by a local resident surnamed Zhang, who discovered his rice paddy had dried out. "We thought something might have happened to the reservoir. I went to the tunnel, and found them dead," he said.

Local police said they died after inhaling carbon monoxide discharged from a generator in the tunnel.

Carbon monoxide is an odorless gas, which if inhaled, can cause headache, nausea, unconsciousness and even death.