A pair of hikers who had been rescued after getting lost in the fog and rain inside a Maine state park drowned on Tuesday night when their car plunged into the water off a boat launch as they were trying to leave.

Amy Stiner, 37, and Melissa Moyer, 38, were found dead inside a minivan in 20 feet of water about 175 feet from the boat ramp on the edge of Roque Bluffs State Park, the Washington County Sheriff's Department said. A dog, a pit bull mix who was with them, also drowned.

Officials say the women, who had just been returned to their vehicle by a game warden, took a wrong turn as they were driving away from the parking area.

"The end of the road becomes the boat landing and they just weren't familiar with it," Washington County Sheriff Donnie Smith told the Kennebec Journal. "It was foggy and rainy and they literally drove off the boat landing right into the water."

Stiner made a desperate call to 911 at approximately 9 p.m., saying they were trapped inside the submerged minivan and that it was filling up with water, according to the Bangor Daily News.

"And then the phone just went dead," Smith said.

Police used GPS data from the cellphone to locate the general area of the van, and called in the Maine Marine Patrol and U.S. Coast Guard to join in the search, but it was too late.

Stiner, who lived in nearby Machias, Maine, was five months pregnant, police said. Moyer, from Sunbury, Pa., was visiting when the tragedy unfolded.

Earlier, Stiner and Moyer had used a cellphone to call for help after they became lost during their hike.

An off-duty firefighter with the Sunrise Search and Rescue team found the pair and their dog on the western shore of the park and took them to a nearby house, Smith said. A game warden then picked them up and brought them back to their vehicle.

The state medical examiner was called to determine the official cause of death, but Smith said he didn't suspect any foul play.

"It's just so easy to do," Smith said." When I got the call last night, I knew what had happened."