With a $61 million shortfall to bridge by the end of June, the Philadelphia School District will let go about 90 school police officers Friday, according to a source familiar with the plan.

Other cuts will also be announced, including administrative layoffs likely to come from regional offices, the source said.

The police officers who will be laid off are per-diem workers who do not earn benefits, though most work every day during the school year.

District spokesman Fernando Gallard declined to comment Thursday.

"As of today, we do not have any layoff announcements," said Gallard.

Michael Lodise, head of the school police officers' union, had not received notice Thursday, but said 90 layoffs "is what I'm hearing."

Some officers already have been reassigned in anticipation of changes. "We're already getting plans in place," said Lodise.

Besides the per-diem officers, the school police force consists of 375 full-time permanent officers. It's a much smaller force than in the past.

The per-diem officers "augmented the force," Lodise said. Losing them will mean some tough schools will have less protection.

Lodise said he feared the implications for school safety.

"It's not going to be good," he said. "We're having a hard time keeping up now with what we have. They're counting on the Philadelphia Police Department to help, but they're so shorthanded with the problems they're having now."

Safety has long been an issue for the district. An Inquirer investigative series found that violence in city schools is widespread and underreported, with 30,000 serious incidents over the last five school years.

Other cuts to fill the $61 million hole have been announced, including drastic reductions to summer school and the recision of a planned pay raise for nonunionized administrative employees. Those workers will also start paying a share of their health insurance; nonunionized employees who make more than $75,000 will also see pay cuts.

Further reductions have been mentioned but not decided upon, including cuts to school psychologists and the elimination of spring athletics, instrumental music, gifted programs, and bilingual counselors.

The School Reform Commission had said cutting the entire school police force would save the district $15.5 million. It's not clear what the per-diem cut would save.

In late January, the SRC hired a chief recovery officer, Thomas E. Knudsen, charging him with restoring the district to sound financial footing and restructuring its operations.

But even with Knudsen at the helm and cuts in the works, City Controller Alan Butkovitz has questioned the district's financial viability.

Butkovitz has estimated the district would have to cut $400,000 a day to make up the $61 million shortfall.

And next year already looks grim. The district faces a budget gap of $269 million for the 2012-13 fiscal year.

Contact staff writer Kristen Graham at 215-854-5146 or kgraham@phillynews.com, or on Twitter @newskag. Read her blog, "Philly School Files," at www.philly.com/schoolfiles.