Two employees in the EPA’s Region 8 headquarters in Denver and one who works at the EPA’s National Enforcement Investigations Center in Lakewood are under investigation for signing the letter, said Kate Tribbett, vice president of the American Federation of Government Employees Local 3607, which represents Region 8 employees.

The Environmental Protection Agency has put more than 100 employees across the nation on administrative leave after they signed a letter opposing Trump administration policies, the EPA said.