Federal Reserve Chair Jerome H. Powell said Thursday the U.S. economy is in an emergency and is deteriorating “with alarming speed.”

His remarks came shortly after the central bank unveiled over $2 trillion in new loans to keep the economy afloat as much of the nation goes into a lockdown to fight the spread of the deadly coronavirus.

“People have been asked to put their lives and livelihoods on hold, at significant economic and personal cost,” Powell said in a Brookings Institution webcast. “We are moving with alarming speed from 50-year lows in unemployment to what will likely be very high, although temporary, levels.”

Powell called for a national discussion about what it will take to reopen the economy, but he urged caution about moving too quickly and triggering another spike in coronavirus cases and deaths. Treasury Secretary Steven Mnuchin has said it’s possible businesses can reopen in May. Powell said sometime after July is more likely.

More than 17 million Americans have filed for unemployment aid in the past four weeks as the nation has entered a national emergency due to the global pandemic, the Labor Department reported Thursday. Powell said the burdens of the shutdown are “falling most heavily on those least able to carry them,” and he vowed to do everything he can to help.