The head of the Centers for Disease Control and Prevention pleaded with Americans to wear masks and adhere to COVID-19 mitigation measures, warning of “impending doom” as cases, hospitalizations and deaths begin to rise again.

Rochelle Walensky, speaking at a press briefing Monday, fought back tears as she outlined a series of warning signals and said she was frightened about a looming fourth wave of COVID cases.

“I’m going to reflect on the recurring feeling I have of impending doom. We have so much to look forward to, so much promise and potential of where we are and so much reason for hope, but right now I’m scared,” she said. “I just worry that we’ll see the surges we saw over the summer and over the winter again.”

She said the U.S. trajectory looks “similar” to that in the EU a few weeks ago, before spikes in cases took hold. She asked elected officials, faith leaders and other influencers for help.

“I’m calling on every single one of you to sound the alarm, to carry these messages into your communities,” she said.

“We do not have the luxury of inaction. For the health of our country, we must work together now to prevent a fourth surge,” she said.

Many states are lifting restrictions at levels the CDC wouldn’t recommend, she said. She will speak to governors on Tuesday and warn them against reopening too quickly. She also cited an uptick in travel as potentially fueling a rise in cases.

Walensky has regularly sounded the alarm as a decline in cases stalled from January highs. Her plea on Monday was her strongest yet. The U.S. is racing to vaccinate adults as new variants of the virus take hold and spread, hoping that inoculations will rise before a new wave kills tens of thousands more.

Walensky said she was speaking “not only as your CDC director but as a wife, as a mother, as a daughter, to ask you to just, please, hold on a little while longer. I so badly want to be done, I know you all so badly want to be done; we are just almost there but not quite yet,” she said. “So I’m asking you to just hold on a little longer, to get vaccinated when you can, so that all of those people that we all love will still be here when this pandemic ends.”