Foul play is suspected in the disappearance of two Kansas women whose vehicle was found abandoned in the Oklahoma Panhandle last weekend, authorities said Friday.

Veronica Butler, 27, and Jilian Kelley, 39, of Hugoton, Kansas, were driving to Oklahoma to pick up Butler’s children to attend a March 30 birthday party in Kansas but never showed up, Tom Singer, the pastor of the church Butler attended, told KOCO-TV.

Hunter McKee, an Oklahoma State Bureau of Investigation spokesperson, said investigators believe foul play led to women’s disappearance based on what was found their vehicle.

McKee declined to say what evidence was found in the vehicle, citing the continuing investigation.

Singer did not immediately return phone calls for comment Friday morning.

McKee said the abandoned vehicle was found by Texas County deputies and referred additional questions to Texas County Sheriff Matt Boley, who did not immediately return a phone call for comment.

The sheriff’s office has turned the investigation over to the OSBI.

“We’re still looking into where and when they were last seen,” McKee said.

McKee said no children are missing.

Investigators are searching the area in Texas County around where the vehicle was found, according to McKee, about 11 miles (18 kilometers) south of Elkhart, Kansas, on the Oklahoma-Kansas state line.

The area is about 260 miles (418 kilometers) northwest of Oklahoma City.