The teenager who filmed George Floyd's arrest and testified in court reacted after Derek Chauvin was found guilty of all three charges in his death.

"I just cried so hard," Darnella Frazier, 18, said in a social media post shortly after the verdict was announced. "This last hour my heart was beating so fast, I was so anxious."

"George Floyd we did it!!" she said. "Justice has been served."

Frazier, a high school student, was walking to Cup Foods with her 9-year-old cousin to buy some snacks on May 25, 2020, when they witnessed police officers pinning down Floyd.

Frazier said she immediately began recording the incident with her cellphone.

"He was in pain," Frazier said of Floyd during her testimony the first week of the trial. "It seemed like, he knew ... he knew it was over for him. He was terrified. He was suffering. This was a cry for help."

During her emotional, tearful testimony, Frazier said she has spent nights agonizing over what she saw.

"I stayed up apologizing and apologizing to George Floyd for not doing more and not physically interacting, not saving his life," she testified.

ABC News' Bill Hutchinson contributed to this report.

“Today, a jury in Minneapolis did the right thing,” former President Barack Obama and former First Lady Michelle Obama said in a joint statement.

But the Obamas also said “true justice is about much more than a single verdict in a single trial.”

“True justice requires that we come to terms with the fact that Black Americans are treated differently, every day,” they wrote. “It requires us to recognize that millions of our friends, family, and fellow citizens live in fear that their next encounter with law enforcement could be their last. And it requires us to do the sometimes thankless, often difficult, but always necessary work of making the America we know more like the America we believe in.”

The Obamas said the verdict was a “necessary step,” but noted that concrete reforms to reduce and eliminate racial bias in the criminal justice system and efforts to expand economic opportunity for marginalized communities are needed.

“And as we continue the fight, we can draw strength from the millions of people — especially young people — who have marched and protested and spoken up over the last year, shining a light on inequity and calling for change. Justice is closer today not simply because of this verdict, but because of their work,” they wrote.

Minnesota Attorney General Keith Ellison, the lead prosecutor in the Derek Chauvin murder trial, measuredly addressed his victory shortly after the jury delivered its guilty verdict.

"I would not call today's verdict justice, however, because justice implies true restoration," Ellison told reporters outside the Hennepin County Government Center. "But it is accountability, which is the first step towards justice."

Ellison thanked the witnesses who testified on behalf of the prosecution, including the bystanders to Floyd's arrest on May 25, 2020, whom he referred to as a "bouquet of humanity."

"They didn't know George Floyd," he said. "They stopped and raised their voices, and they even challenged authority, because they saw his humanity. They stopped and they raised their voices because they knew that what they were seeing was wrong. They didn't need to be medical professionals or experts in the use of force. They know what was wrong. And they were right."

Ellison also addressed Floyd's family, who had to "relive again and again the worst day of their lives."

"I'm profoundly grateful to them for giving us the time we needed to prosecute this case," Ellison said. "They have shown the world what grace and class and encourage really look like. Although verdict alone cannot heal their pain, I hope it's another step on the long path toward healing for them.

To the 14 members of the jury, Ellison thanked them for their time and attention "to carefully listen to the evidence."

"They answered the call, and they served in a landmark trial," he said, and asked that people respect their privacy if they so desire.

Ellison referred to his legal team as "all Michael Jordans."

"We presented the best case that we could, and the jury heard us, and we're grateful for that," he said. "We had the sole burden of proof in the case, and history shows that winning cases like these can be difficult."

With sentencing in the coming weeks, the attorney general said "this is not the end." He also said his office expects to present another case, but did not go into any detail.

Members of the Congressional Black Caucus reacted to the guilty verdict in the Derek Chauvin case outside the Capitol on Tuesday, welcoming the news while vowing to press forward with police reform.

"This verdict we certainly agree with, guilty on all charges," Chair Joyce Beatty, D-Ohio, said. "But we want our message to be very clear that this is just the first step. We know clearly that justice has been delayed."

Freshman Rep. Cori Bush, D-Mo., said the verdict "should be the regular thing" rather than a surprise international news headline. "All we’re doing is saying our lives matter."

“Step one is the verdict, step two is the sentencing,” Rep. Karen Bass, D-Calif., a leader of police reform legislation negotiations, added. "Now we have to focus on transforming policing in the United States."

-ABC News' Ben Siegel