California election officials have received reports that unofficial ballot drop boxes were placed in several counties and said these set-ups are illegal.

Secretary of State spokesman Sam Mahood said boxes were reported in Fresno, Los Angeles and Orange counties at locations including political party offices, candidate headquarters and churches and state officials were looking into their origin, the Orange County Register reported. The agency issued a memo to county registrars this weekend clarifying that unofficial drop boxes are illegal and ballots must be returned by mail or to official polling places, vote centers or ballot drop-off locations.

For a list of official ballot drop-off boxes in Long Beach, click here (or see map below).

The memo comes after a regional field director for the California Republican Party in Orange County supporting the congressional campaign of Michelle Steel posed in a social media photo with a box labeled “official ballot drop off box” and encouraged voters to message him for locations to drop their ballots, the newspaper reported. Steel, a county supervisor, is challenging Democratic Rep. Harley Rouda for his seat.

There was a report about a similar box at a church in the Los Angeles County community of Castaic. The church posted on social media the box was “approved and brought by the GOP,” the paper said.

In Orange County, the district attorney is investigating and has confirmed at least two unofficial boxes were placed in at least two different cities, said Kimberly Edds, a spokeswoman for the district attorney’s office. Neal Kelley, the county’s registrar of voters, said official drop boxes are clearly recognizable and carry the official county elections logo. He said it wasn’t clear how many voters had used these unofficial boxes but after receiving reports about them he notified the state and district attorney’s office.

“It would be like me installing a mailbox out on the corner – the post office is the one that installs mailboxes,” Kelley told the newspaper.

Lance Trover, a spokesman for Steel’s campaign, deferred questions to the state Republican Party.

A spokesman for the state Republican Party said the party would comment on the issue later on Monday. The party questioned in a post on Twitter this weekend what would be wrong with a group providing an option for associates to drop off ballots in a safe location rather than handing them to an individual.

California Democratic Party Chair Rusty Hicks said his party would defend the right of all registered voters to cast their ballots this year.

“Sadly, this is par for the course from the Republican Party — well-versed in making it harder, not easier for Californians to vote,” he said in a statement.

Here’s a map of official Long Beach ballot drop-off boxes: