WINDSOR (AP) — Police in Maine say one woman and two men have been found dead after their Jeep became stuck in a bog in Windsor.

The Kennebec County Sheriff’s Department tells the Kennebec Journal  that the three went four-wheeling and were last seen alive around 7 p.m. Friday. Their bodies were discovered Saturday evening. Their identities had not been released by Sunday afternoon.

The bodies were discovered in a Jeep about 300 yards from the road. Capt. Dan Davies of the Kennebec County Sheriff’s Department says a preliminary investigation suggests the group may have been overcome by carbon monoxide poisoning in the vehicle. The Jeep’s roof was on.