A chemical leak that sent 60 people to the hospital and forced hundreds of people to flee their homes has been blamed on an employee error.

Mayor Wade Kapszukiewicz announced the cause of the tank leak at a news conference on Friday and said that all remaining evacuation orders in Toledo , Ohio .

The chemical leak happened Tuesday night when an employee of MC Tank Transport “introduced a temperature level to the tank in the process of trying to transfer the liquid" that caused a chemical reaction, the mayor said.

MC Tank Transport said the tank contained glycidyl methacrylate , which it described as “an industrial chemical used to make certain plastics, paints and coatings perform better.”

A plume of smokes rises from MC Tank Transport Inc., where a chemical tank exploded overnight, prompting hundreds of residents to evacuate or shelter in place amid concerns about a potential toxic release, Wednesday, Oct.…