A nationwide search continued Friday for a 15-year-old boy and his 13-year-old girlfriend, who fled their homes with one family's minivan, $680 in cash and a dog named Mandy.

They may be bound for Colorado or California, authorities said.

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 northwest of Detroit.

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McConnell's father told FOX News his daughter was recently diagnosed as bipolar and does not have her medication with her.

"She will be going through extreme highs and lows probably," John McConnell said. "She just needs to come home and be safe. Her mom and I are worried sick to death."

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 promising to call. He had not done so by early Thursday, The Flint Journal reported.

"My son is very much in love with Hannah," Mary Wismer said.

John McConnell said the night before their daughter ran away they had an argument about her relationship with Petherbridge .

"He's two years older and we told her it wasn't appropriate," John McConnell said. "Never in our wildest dreams did we imagine they would actually run away with one another like this."

Julie McConnell said her daughter "believes the world revolves" around them.

Julie 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.

The Associated Press contributed to this article.