SOLANO COUNTY -- Contra Costa County Sheriff's officials discovered the bodies of two men Monday afternoon aboard a houseboat in the Delta, though it remains unknown if they met with foul play, authorities said.

Authorities came upon the grisly discovery about 1:30 p.m., and contacted Solano County Sheriff's deputies to investigate the crime about five miles south of Rio Vista, Solano County Sheriff's Deputy Daryl Snedeker said. Sheriff's investigators, along with crews from the Coast Guard and Marine Patrol were on scene about 6 p.m.

"We're in the very early stages of the investigation." Snedeker said. "We're on the water trying to conduct an investigation, and we've lost all daylight, so it's going to be difficult."

Snedeker said it is unclear at this time if either of the men met with foul play. Snedeker and Contra Costa Sheriff's spokesman Jimmy Lee declined to say why the Contra Costa officials were in Solano County.

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Contact Erin Ivie at eivie@bayareanewsgroup.com. Follow her at Twitter.com/erin_ivie.