Jessica Heeringa, 25, has not been seen since Friday night, the Detroit Free Press reported. A customer told police he found the Exxon Mobil station in Norton Shores empty shortly after 11 p.m., less than half an hour after Heeringa made a final sale.
Police have been using helicopters to search for a gray or silver minivan witnesses said was at the station about that time. While the station did not have video surveillance, they have identified what may be the vehicle from surveillance cameras nearby.
The driver was a man who appeared to be in his 30s and was wearing a bright orange or red shirt, police said.
Norton Shores Police Chief Daniel Shaw said investigators believe Heeringa and her abductor knew each other.
"We're thinking whoever took Jessica definitely knew her or she knew them in some way either as acquaintances or a customer that she had a rapport with," he said.
Investigators found Heeringa's wallet and vehicle still at the station. She appeared to be preparing to close for the night.
Shaw said there was no evidence Heeringa left voluntarily, although there were no signs of a struggle. Relatives have described her as a loving mother who would not have walked away from her young son, he said.