Surveillance cameras captured what happened outside Reliance Market at 20th and Castro streets.
A person appears to "fish" for items inside the mailbox.
Reliance Market's owner saw the crook drop at least one ballot he fears other ballots might have been stolen and discarded.
RELATED: What's the difference between an absentee and mail-in ballot?
"And then I get really upset when I see this is happening," said market owner Sami Wahab. "We really need to have a fair election."
The store owner found one ballot and gave it to his postal carrier.
If you know anything about Friday morning's crime, U.S. Postal Inspectors want to hear from you.
Californians can learn how to track their 2020 ballots here.
Get the latest stories and videos about the 2020 election here.
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