Minneapolis Public Schools officials admit they failed to vet literacy training materials that exhibit racial and cultural stereotypes.

Earlier this month, some teachers received training to prepare them to use a new early literacy curriculum. They received "Little Books" that they could use to teach literacy skills to the district's kindergarten through second grade students.

But the books contained images that teachers found offensive. A book titled "Lazy Lucy" showed a black girl on the cover, and another book called "Nieko, the Hunting Girl," with a picture of an American Indian girl and her father.

"Due to staffing shifts and the desire to get a program in place for the new school year, the books were not comprehensively vetted," said Interim Superintendent Michael Goar in a statement. "We now know this was a mistake. We regret that this happened. We will do better."

The books were part of a larger curriculum that the district purchased in July from a Utah-based company called Reading Horizons. The district paid the company $1.2 million.

The district says they immediately pulled the books after teachers raised concerns, and no students were exposed to the materials. District officials also say they have asked Reading Horizons to write new books.

"Teachers will be central to that conversation," said Chief Academic Officer Susanne Griffin. "These revisions won't just be for Minneapolis, but for districts across the country."

The issue was first raised by a local education blogger, Sarah Lahm. Teachers and community members were also upset that the district contracted with a company that identifies one of its core values as "faith." The Reading Horizons website says a employee survey showed its employees "believe in a higher purpose of life. We seek to do His will and to achieve balance in our lives."

The district says what was described "as employee responses to an inquiry about core values should not be characterized as corporate values."

"The values are not promoted through the program," Griffin said.

David Branch, a former administrator, wrote on the district's Facebook page that "this is an embarrassment that cannot be fixed by changing the books."

"Show that you have courageous leadership and take action to not work with this company," Branch wrote. He posted the pictured example above on Facebook.

Goar said for the time being the district will continue to work with Reading Horizons.

"Research shows this program has been successful in improving student outcomes across the country, including outcomes in diverse district like ours."

Reading Horizons officials did not return messages seeking comment Thursday. On the company's Facebook page, officials apologized and vowed to change the content of their books.

"It would be a shame for anyone to avoid our products while we work to resolve our weakness and work to better represent a variety of cultures," the company wrote.