MINNEAPOLIS (AP) — A large Minnesota school district has been forced to return to distance learning after an outbreak of COVID-19 among its transportation workers.

Bloomington Public Schools brought back preschoolers through second graders on Jan. 19, and had planned to bring back third to fifth graders on Monday. But the district informed parents on Thursday evening that the plan will be on pause until Feb. 12.

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Bloomington’s retreat underscores the unique challenges of protecting bus drivers, many of whom are at higher risk of severe illness because of their age. Drivers are often retirees working for supplemental income.

“We want nothing more than for our students and staff to be in schools learning safely,” Superintendent Les Fujitake said in an email to parents. “We understand this is yet another disruption for our families in an already demanding year.”

The Minnesota Department of Health reported another 28 COVID-19 fatalities Friday and 1,145 more cases, raising the state’s death toll to 6,168. The new cases were the result of nearly 46,000 tests for a positivity rate of 2.6%. The weekly positivity rate remains below the 5% threshold health officials use to determine if the outbreak is under control. The state’s test positivity rate peaked at more than 14% in November.

Health care providers across the state have administrated 444,164 vaccine doses. There are 345,636 people who have received one dose and 96,842 who have had the required two. Health officials hope to soon finish inoculating health workers as well as residents and workers at long-term care centers.

Minnesota allowed school districts around the state to resume in-person learning for elementary grades starting Jan. 18. Many districts across the state have done so, at least partially.

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“There’s always a tremendous amount of hope, bringing students back to school,” Bloomington schools spokesman Rick Kaufman said. “It’s gut wrenching to now have to move to distance learning. But again, this is the up-and-down of COVID-19 and its impact on our communities.”

At least eight people in the Bloomington district’s transportation department have tested positive, and more than a dozen employees are under quarantine, he said.

Bloomington district is believed to be the first district in the Twin Cities area to experience an outbreak since returning to in-person learning last week, said Scott Croonquist, executive director of the Association of Metropolitan School Districts. But he said school leaders know it could happen at any point.

“It’s kind of something that every superintendent is holding their breath over,” he said.

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