Five activists were arrested and charged with trespassing Monday morning after chaining themselves together and blocking the entrance to a KCBX Terminals Co. petroleum coke facility on Chicago’s southeast side.

These efforts represent an escalation of tactics in a more than two-year struggle to force pet coke out of Chicago.

The protesters were released Monday afternoon. All five are scheduled to appear in Cook County Court on December 23. In a statement, KCBX spokesman Jake Reint said the company has “always sought to operate our facility with the utmost respect for our neighbors and the environment, and that remains the case today.”