CHICAGO (AP) — Hundreds of Chicago students staged a walkout Friday, saying there weren’t enough precautions in place to protect them from COVID-19 despite an agreement between the teachers union and school district to return to classrooms.

The walkout at schools across the city culminated outside district offices downtown, where the students waved signs, chanted and briefly blocked traffic.

“Hey, hey, ho, ho, Lori Lightfoot’s got to go,” they said, a reference to the Chicago mayor.

The union voted last week to switch to remote instruction due to an increase in COVID-19 cases and what they said were insufficient safety measures. Administrators in the nation’s third-largest school district canceled classes for five days as a result. Lightfoot insisted in-person instruction was best for students and called the union’s action an illegal work stoppage.

In-person classes resumed Wednesday after an agreement on a safety plan that includes metrics to shut down individual schools during outbreaks and expanded testing.

While masks are required inside schools, the protesters said some students don’t have masks or wear them inconsistently. They also want better access to COVID-19 testing and technology for remote learning.

“We want online schooling and the ability to be kept safe … while we’re trying to get an education,” student Jaden Horton said.