The released figures are much higher than forecasts cited by various media, as economists expected the number of claims to stand at around four million.
"In the week ending March 28, the advance figure for seasonally adjusted initial claims was 6,648,000, an increase of 3,341,000 from the previous week's revised level," the statement said.
According to the department, the latest figures mark "the highest level of seasonally adjusted initial claims in the history of the seasonally adjusted series."
The data was adjusted as all states reported a surge in claims for the previous week, with the most significant increase seen in Pennsylvania (more than 300,000), Ohio, and Massachusetts.
Nearly 3.3 million claims were filed in the week ending March 21, smashing the 1982 record, when the number of initial weekly filings reached 695,000.
The record unemployment claims –that hit almost 10 million for the two last weeks of March– come as the U.S. battles the devastating impact of the new coronavirus pandemic on its economy. Lockdowns across the country have shut down many businesses and resulted in massive layoffs.
The U.S. has the highest number of COVID-19 cases in the world, with over 240,000 people infected, out of more than one million worldwide.