Four people have been arrested and charged with murder in connection with the disappearance of two women in Oklahoma, authorities announced on Saturday. The remains of two bodies have also been found, although they have not been identified yet, officials said Sunday.

Veronica Butler, 27, and 39-year-old Jilian Kelley were last seen together in a vehicle that was later found abandoned by the highway in a rural part of Texas County, Oklahoma.

Tad Bert Cullum, 43, Tifany Machel Adams, 54, Cole Earl Twombly, 50, and Cora Twombly, 44, were all arrested Saturday and charged with two counts each of first-degree murder and kidnapping and one count of conspiracy to commit first-degree murder, the Oklahoma State Bureau of Investigation said. 

Authorities did not provide any further details, including possible motivations, connections to the victims or evidence that led to the arrests of the four individuals.

On Sunday, two bodies were discovered in Texas County, the Oklahoma State Bureau of Investigation said. Both bodies were still awaiting identification.

Butler and Kelley were last seen traveling together in a vehicle on March 30 before they disappeared, according to a missing persons alert released by the Texas County Sheriff's Department. They had traveled from nearby in Kansas to pick up Butler's children, CBS affiliate KWTV reported. The missing persons alert said neither "made it to the pick up location." 

Butler had been involved in a custody battle, KWTV reported, but it was not clear if that had anything to do with her disappearance.

According to the state's bureau of investigation, the car the women were traveling in was found abandoned along the side of the road near Oklahoma State Highway 95, right by the border between Oklahoma and Elkhart, Kansas.

A few days after the car was found, the Oklahoma State Bureau of Investigation said that "investigators believe there was evidence to indicate foul play." It did not elaborate on what that evidence was.