It was the "largest monthly drop in the 101-year history of the index, as the COVID-19 (coronavirus disease 2019) pandemic led many factories to slow or suspend operations throughout the month," the Fed said.
The auto sector took the biggest hit, plunging more than 70 percent, according to the data.
Overall manufacturing output fell 13.8 percent in the month and is 18 percent below April of last year.
Decreases of around 20 percent were recorded by primary metal products, aerospace and miscellaneous transportation equipment, and by furniture and related products, according to the report.
With demand for energy collapsing amid the pandemic shutdowns, the Fed said oil and gas well drilling fell 28 percent, its largest drop on record dating back to 1972.
Factory capacity in use fell nearly 10 points last month to 61.1 percent, below the previous record low set in June 2009 amid the global financial crisis.