President-elect Donald Trump's incoming administration plans to immediately order a series of deportation raids targeting illegal immigrants, according to multiple reports Saturday.

The size of the planned immigration raids is unclear, but they would be the opening step in the president-elect’s goal of overseeing the largest deportation program in history.

The Trump administration is reportedly planning to begin its promised campaign of unprecedented mass deportations with a series of raids in Chicago. The raids will begin the day after the Republican is inaugurated, The Wall Street Journal reports.

Many immigrant advocacy groups in the city and suburbs have been reaching out to undocumented immigrants ahead of Trump's inauguration, in an effort to get ready for what might be coming.