Early Friday, she was shaking her head in disbelief at a top Trump administration official calling relief efforts in Puerto Rico a "good news story."
By the end of the day, San Juan Mayor Carmen Yulin Cruz was issuing a "Mayday" call for help for the U.S. citizens on the hurricane-ravaged island, decrying the administration's response to the disaster.
"I am mad as hell," said Cruz, standing in front of pallets of water sent for distribution. " ... We are dying here. And if we don't get the food and water into people's hands, we are going to see something close to a genocide."
When she studied public policy as a Carnegie Mellon University graduate student in the 1980s, Cruz learned to identify problems and solutions based on the evidence at hand.
As mayor of Puerto Rico's capital, she has been applying that approach in the wake of the devastation of Hurricane Maria.
In a Friday morning interview with CNN, she said: "This is, dammit, this is not a good news story. This is a people-are-dying story."
And she listed some of the evidence:
"When you're drinking from a creek, it's not a good news story. When you don't have food for a baby, it's not a good news story. When you have to pull people down from their buildings, because -- I'm sorry, but that really upsets me and frustrates me."
Cruz's response doesn't surprise Jon Nehlsen, associate dean at CMU, who met her about three years ago during a campus visit.
"She is a force of nature," said Nehlsen, of the Heinz College of Information Systems and Public Policy at CMU. "She's probably not 5'2", but she's this ball of energy, very charismatic. You can just tell she exudes leadership qualities."