Heidi Planck, 39, went missing on Oct. 17.
Heidi Planck
Heidi Planck
| Credit: Facebook

A California mother disappeared after attending her 10-year-old son's football game and hasn't been seen since.

Family members and police are asking for help finding Heidi Planck, 39, who went missing on Oct. 17.

"Heidi's family and friends are concerned for her safety," an LAPD statement says.

Planck's ex-husband Jim Wayne told NBC's Dateline that Planck left the football game in Downey at halftime, and that during the game, she had looked on edge.

"She was a little bit antsy, yes. I don't know why," Wayne said. "All I know is that was the last time I saw her or talked to her."

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The Los Angeles Police Department said she didn't pick up her son from school in West Los Angeles three days later, on October 20.

"She's a devoted mother who would never, ever leave her son," Wayne told Dateline. "We have a 10-year-old boy at home that's looking for his mom and we just need to find her."

Heidi Planck
Heidi Planck

Adding to the mystery, Planck's dog was found on the 28th floor of an apartment building in Downtown Los Angeles.

Friends and family fear that foul play might be involved in her disappearance, NBC reports.

"I just want to know where my friend is," close friend Danielle Nadolny told Dateline. "He needs his mother. We all need her home safe."

Planck's friend Natalie John told Fox News they will never give up searching for the missing mom.

"We're not going to give up until we can hold you, we can hug you," John said. "We love you, Heidi."

"I want you to know that you have so many friends that love you," she said. "Friends that we've never met, that we've met now and we all will be friends. We're kind of stuck together in this. But we all love you. We're rooting for you. We want to see you."

Planck, who is white, 5 feet 3 inches tall and weighs about 120 lbs., with blond hair and blue eyes, was last seen wearing jeans and a gray sweater.