PLEASANTON -- Amador Valley High School officials held multiple forums with upset students and parents Friday after a "seating irregularity" forced the California College Board to invalidate advance placement tests taken by 400 students.

The state's Educational Testing Service, which works with the College Board to administer the tests, investigated two testing rooms at the high school and found that students were not seated the required 5 feet apart and that not all students were facing the same direction. Both violate testing regulations, according to a press release from the Pleasanton Unified School District.

The other test rooms at the school followed seating guidelines, and so 75 percent of the AP exams remain valid. But about 400 students' tests were invalidated, and they will be "given the opportunity to retake their tests next week," according to the release.

"It's not right (that the kids have to retake the tests). The kids work so hard to prepare for the tests," said Sherry West, parent of an 11th-grader at Amador Valley High. "They should have a choice ... If they didn't feel good about their score, they could take it again. They shouldn't be asked to take it again."

It's unclear who will have to pay any testing fees for the retaking -- whether the district, the ETS or parents will be asked to foot the bill -- but one parent said the college board has offered parents a full refund for the first tests.

"It's sad. It's not fair," said Rekha Gupta, whose son, a 10th-grader, will have to retake three of four AP tests while preparing for the SATs simultaneously. "The college board said they would give us a full refund. Who wants a refund?"

It's also unclear who made the mistake of arranging the students' seats in the wrong fashion and what, if any, consequences will ensue.

The school held two forums Friday with affected students and parents. A third will be held at 10 a.m . Saturday at the school.

Reporters weren't allowed to attend the Friday meetings, and district officials have been reluctant to comment about the incident.

School district Assessment Coordinator Nicole Steward said the district had found "no cheating" to have taken place but said the district wasn't prepared to comment further.

"Our main focus at this time is on the children," she said.

Calls to school board members were not immediately returned. Superintendent Parvin Ahmadi was in meetings throughout the day and unable to get back to reporters, her administrative assistant said.