Update: While the district reported normal bus operations in the morning, some drivers did not work afternoon routes. As of 4:10 p.m., the district reported 22 routes with delays out of 850. By 5:40 p.m., the district reported that all routes had been completed.

Some Denver school bus drivers may not come to work Wednesday in response to a physical altercation between a parent, bus driver, and bus aide last week, according to a letter the district wrote to families Tuesday evening. Earlier on Tuesday, the Denver district attorney announced that the parent, who was arrested on suspicion of assault, would not face criminal charges.

The letter says Denver Public Schools leaders are “having conversations to ensure all bus drivers attend work,” but district leaders expect delays on bus routes Wednesday.

“We are doing everything we can to avoid cancellations, and we expect there may be some delays felt across bus routes tomorrow if we are short drivers,” the letter says.

Students with disabilities who receive bus transportation “will be a top priority,” the letter says. The district does not anticipate delays on routes driven by outside companies.

On Wednesday morning, the district tweeted that bus operations appear to be normal.

Wednesday is Count Day, when student enrollment is measured for purposes of state funding, potentially raising the stakes of a sick-out. However, state regulations allow for students to be counted within an 11-day count period if they miss school on Count Day.

The physical altercation happened on Sept. 18 on the way home from school in northeast Denver. According to a police report, the bus driver pulled over between regular stops after students on the bus became “unruly.” Alerted by texts from their children, parents went to that location, but the bus driver and an aide did not let students off the bus.

A chaotic scene unfolded, with children screaming and the bus staff blocking the rear door. Parent Brandi Martin, 32, jumped onto the bus to get her daughter. In a video of the incident, the driver or the bus monitor appeared to grab Martin and shove her into a seat. She broke free and tried to climb further into the bus, but the man grabbed her by the arm and later by the hair. She broke free again and threw some punches before exiting the bus, clutching her head.

Martin was arrested but will not face charges. The bus driver and aide were placed on administrative leave while the district conducted its own investigation. District spokesman Will Jones said the pair remain on paid administrative leave as of Tuesday. Asked if either employee could face disciplinary action, Jones said personnel matters are confidential.