By CBS3 Staff

PHILADELPHIA (CBS) — The Philadelphia School District has once again delayed the return to the classrooms. Students and staff were set to return for in-person learning on Feb. 22, but hybrid learning has been delayed one week.

A fourth attempt at bringing students into a hybrid learning setting has been postponed until March. 1.

READ MORE: Teenager Killed In Trenton Shooting Identified As Shemiah Davis, Mercer County Prosecutor's Office Says

“I’m deeply disappointed to share due to ongoing third-party mediation between the district and the Philadelphia Federation of Teachers, we will be delaying the return of students into our schools,” Superintendent Dr. William Hite said.

Hite made the announcement Wednesday on the district’s website.

“As parents and guardians, you know all too well that many of our students are struggling socially, emotionally and academically after engaging with their teachers and peers through a computer screen for almost a year,” Hite said. “Safely returning our kids to their schools in phases is a crucial step to help restore the sense of community and connectedness that so many of our students want and need.”

Teachers were to return to schools on Feb. 8, but the school district is now in the midst of mediation between a third-party outside entity and the Philadelphia Federation of Teachers after teachers felt it was still too unsafe to return to classrooms.

Some 9,000 pre-K to second-grade students were set to return to classrooms next week but because of mediation, teachers have not returned to school buildings to ready for their return.

“Because we have not had the ability to put educators in all classrooms to prepare for students is the reason we’ve had to push that date back,” Hite said.

READ MORE: Runners Train At Art Museum For Philadelphia's Upcoming Marathon

School district officials still believe it’s safe to bring kids back into schools, citing layers of security measures put in place like plastic barriers surrounding desks, ample PPE for classrooms, hand sanitizing stations and social distancing signage, and another layer of protection will also be put in place.

“We’ve announced rapid testing plans for students and staff, and the start of COVID-19 vaccine availability for teachers and other staff as two additional layers of safety in our multilayered health and safety plan,” Hite said. “We’ve invested $65 million in personal protective equipment for students and staff, touchless hand sanitizer stations, plexiglass partitions, ventilation repairs and enhancements for fresh air flow, social distancing signage, and other layers of safety that are proven to keep the level of virus transmission in schools low. That’s in addition to $250 million to address lead and asbestos and make other improvements.”

Thousands of teachers have begun receiving COVID-19 vaccination appointments that will begin next week at Children’s Hospital of Philadelphia and several school buildings around the city.

“Having in-school testing and having an offering of a vaccine to people who are working in school settings, this is an amazing moment to begin to return our kids back to in-person learning,” Dr. Susan Coffin with CHOP said.

City Council members are holding a special hearing to address school reopening plans, establishing guidelines for a safe and comprehensive plan to eventually bring all 120,000 students back into schools.

“We really want to focus our conversation on what it takes to get to a full reopening of schools,” Councilmember Helen Gym said.

MORE NEWS: Triple Shooting In Fairhill Leaves 1 Dead, 2 Hospitalized, Philadelphia Police Say

CBS3’s Natasha Brown contributed to this report.