The Texas Education Agency has apologized after fifth graders discovered F-bombs on the state-mandated STAAR test.

"This is in no way acceptable or appropriate, and we deeply regret that these images appeared on the test. We apologize to all our parents and students, and in the spirit of continuous improvement, we pledge to ensure this issue never occurs again," TEA spokeswoman DeEtta Culbertson said in a statement.

The F-words were first pointed out by students who took the reading portion of the State of Texas Assessments of Academic Readiness test on April 10.

"A passage with embedded images of a graffiti park appeared as part of field testing for some fifth-grade Texas students. After the test was administered, TEA discovered that two of the included images contained vulgar words in very small lettering," Culbertson said in a statement.

The TEA said it designs multiple versions of the test. Culbertson declined to say how many versions were created citing it is as part of the test's security.

The agency distributed 413,290 test booklets. Of those, the images impacted 15,697.

The TEA's apology came after learning that students had spotted the obscenities on the test, according to Culbertson.

What is the STAAR test?

The controversial standardized tests are administered in multiple subjects across various grade levels in public schools.

Results are used by the state to help determine grade-level readiness, student achievements, and for rating educators and schools.