CHICAGO (CBS)– The Chicago Teachers Union rally was underway as thousands of protesters march through The Loop Thursday.

4:05 p.m. 

2:40 p.m.

1:30 p.m.

Large crowds are gathered outside of Chicago Public Schools Headquarters on Dearborn Street.

Due to the crowds, Madison Street is closed between State and Dearborn Streets. Officials say traffic delays should be expected and demonstration activity may go through rush hour.

Chicago police said traffic has been rerouted.

Marchers moved to the street as the rally continues.