Gage Petherbridge, 15, and Hannah McConnell, 13, left notes and journal entries saying they were running away together, according to their mothers. They live in Genesee County's Vienna Township, about 65 miles north-northwest of Detroit.
Mary Wismer said she woke up Saturday morning to find her son, her minivan and his cocker spaniel gone. She said her son also took clothing, food and his Xbox 360 video game system.
Soon after, police arrived and said Hannah's parents had just reported her missing.
Wismer said her son, a ninth-grader at Clio High School, left a note apologizing and promised to call. He had not done so by early Thursday, The Flint Journal reported.
"My son is very much in love with Hannah," Wismer said.
Julie McConnell said her daughter "believes the world revolves" around them.
She said she worries because her daughter, an eighth-grader at Carter Middle School, has bipolar disorder and left without her medicine.
McConnell said Hannah took $100 from her purse when she left, and Wismer said Gage has about $580 in cash he got for Christmas.
Gage has had his learner's permit since June and is a very cautious driver, his mother said.
Neither teen has run away before, the mothers said.
"We have reason to believe they may be in the area of Huntington Beach southwest of Santa Ana on the coastline in Orange County, California," said Genesee County sheriff's Capt. Chris Swanson.
