SACRAMENTO  (AP) — Students at nearly 250 California schools posted photos on social media websites while they were taking standardized tests, again prompting questions about testing security, state education officials said.

The most serious issues arose at 16 schools where photos were posted containing actual test questions or answers.

Deputy Superintendent Deborah Sigman told reporters Friday that officials remain confident the Standardized Testing and Reporting (STAR) results are still valid and said the incidents involved a small number of the students tested.

"It looks to us as though most of these postings were about gaining some attention and communication with peers, and not an active (attempt) to try to game the system in terms of the assessment," Sigman said.

In addition to photos revealing test questions or answers, Sigman said other posts by students at 242 schools depicted things unlikely to jeopardize exam results, such as test booklet covers or "bubble art," which she described as students filling in bubbles to craft a message.

The Sacramento Bee first reported Friday that results from those schools are now flagged with a red warning message next to their test results. It notes "a security breach involving social media" was identified at the school and states: "Caution should be used when interpreting these results."

Results from the 16 schools where students posted actual test content also included the warning that the school's accountability rating could be impacted. Those schools also could become ineligible for academic awards.

The department will be releasing its statewide accountability reports within the next few weeks.

Among the 16 schools linked to postings of test materials is San Francisco's Lowell High School, a high-achieving public magnet school. A person answering the school's main telephone line Friday said staff members were in training and unavailable to take phone calls.

Others include two Los Angeles Unified schools — Alexander Hamilton Senior High and Alliance Cindy and Bill Simon Technology Academy High— as well as schools in Burbank and Anaheim. Officials with the Los Angeles Unified School District did not immediately return a voicemail left on the media contact line.

This year's cases include slightly more schools than a similar discovery last year. Online postings involving test materials were found from students at 216 schools, with posts from 12 schools including legible test questions or answers.

The discovery delayed the release of last year's scores for two weeks. In response, the Department of Education enacted new security measures to monitor the use of electronic devices.

Students generally are not allowed to have electronic devices during standardized tests.

Sigman said officials believe the number of online postings discovered may have increased because of the department's efforts to monitor social media websites during testing.

She noted that nearly 4.7 million California students participated in standardized testing this year, saying the number of incidents is "a low number given the kind of social media that students have access to."

The department may step up its efforts to monitor online postings and to train districts on what to look for during testing, Sigman said.

"We take this very seriously and we want to make sure schools and administrators are appropriately monitoring test administrations," Sigman said.