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WASHINGTON — Dr. Deborah Birx, White House coronavirus response coordinator, said Wednesday that there are encouraging signs that parts of the U.S. may be flattening their curves, but she warned that people shouldn't start going out and socially interacting.

In an interview with Savannah Guthrie on the "TODAY" show, Birx said that California and Washington state began social distancing very early and that their "curves" — the lines on graphs projecting the number of people who will contract COVID-19, the disease associated with the virus, over time — are "persistently flat, and that's very encouraging."

New York and New Jersey, meanwhile, had a "logarithmic rise in the number of new cases," she said.

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"We're seeing that stabilizing, and that gives us great encouragement," Birx said.

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Birx acknowledged a rising death toll, but she said the numbers reflect people who were infected by COVID-19 two to three weeks ago, before some of the strict guidelines were implemented. Still, she said, a number of metro areas are struggling.

"What's really important is that people don't turn these early signs of hope into releasing from the 30 days to stop the spread — it's really critical," she warned. "If people start going out again and socially interacting, we could see a very acute second wave very early."

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Asked whether 30 days of social distancing will be enough, Birx wouldn't say whether the Trump administration plans to extend the guidelines. She said it is evaluating data closely and hopes to learn from California and Washington "how different releases could occur by geographic area."

Birx's remarks came a day after the U.S. suffered its deadliest day of the pandemic so far, with nearly 2,000 deaths from Tuesday to Wednesday. The national death toll stood at nearly 13,000 in NBC News' tally on Wednesday morning.