SUNNYVALE — Spark Charter School, where a teacher’s aide was arrested this past week on suspicion of molesting a student, has been ordered to temporarily close until background checks on teachers and other employees are complete.

The school announced Saturday that the Santa Clara County Office of Education ordered Spark to close Monday, until the office can approve teachers’ fingerprint tests. It wasn’t immediately clear why the school opened Aug. 18 without having completed those checks, required by its charter and also by the state.

On Friday, Jonathan Chow, 18, was arraigned on child pornography charges, according to Santa Clara County Deputy District Attorney Jaron Shipp.

Chow, of Cupertino faces one count each of sexual penetration with a child under the age of 10, possessing more than 600 images of child pornography, and inducing a minor’s involvement in child pornography. He also faces two counts of lewd contact or lewd contact on a child by force, violence, duress or fear.

Sunnyvale officers arrested Chow about 5 p.m. Tuesday at Spark, where he worked as a lunchtime monitor and teacher’s assistant in the extended-care program.

Spark, in its first year of operation, occupies part of the campus of Columbia Middle School, at 739 Morse Ave. It has 160 students in kindergarten through sixth grade.

The alleged assault on an 8-year-old girl happened earlier in the day, according to Shipp. The child reported the incident to her parents and school employees, he said.

Shipp said the girl was brave for quickly notifying adults. “She knew what she was forced to do was wrong,” Shipp said.

While the Santa Clara County Board of Education authorized Spark’s charter, it is up to the charter school’s board and administration to comply with conditions such as conducting employee background checks. “We don’t oversee day-to-day operations of this charter,” county Office of Education spokesman Ken Blackstone said.

Office of Education officials visited the school on Thursday and Friday, Blackstone said, and discovered the lapse in fingerprinting.

“That led to us immediately telling them they would need to close the charter until that could be rectified” or risk revocation of their charter, Blackstone said.

According to an emailed statement from Spark Superintendent-Principal Danni Tsai, in early July, Spark applied to the California Department of Justice for an identification number that would allow its teachers to be fingerprinted but did not receive the ID number until Friday.

“We were stymied by not getting our number,” Spark board member Laura Stuchinsky wrote in an email.

According to the school, teachers and other staff were fingerprinted Friday, but the results may not be available for at least 72 hours.

Stuchinsky noted that Spark teachers had previously been fingerprinted, during training and at other schools. However, state law requires that they be fingerprinted again when they are hired by a new district. Spark will reopen when the results are received, the statement said.

In May, an employee of the County Office of Education was arrested on charges of pornography and child molestation. While the education office said that Edgar Covarrubias Padilla had been fingerprinted and passed a background check, questions were raised about safety measures at Walden West environmental camp, where he worked.

Bay City News Service contributed to this report. Contact Sharon Noguchi at 408-271-3775. Follow her at Twitter.com/noguchionk12.