WATCH: Florida school shooting survivor Emma Gonzalez slams politicians, NRA in emotional speech

WATCH: Florida High School Shooting Survivor Talks About NRA

A survivor of Wednesday's deadly school shooting in Parkland, Florida, slammed President Donald Trump, lawmakers and the National Rifle Association in a scathing speech Saturday at an anti-gun rally in Fort Lauderdale.

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"Every single person up here today, all these people should be home grieving," said Emma Gonzalez, a student at Marjory Stoneman Douglas High School. "But instead, we are up here standing together because if all our government and president can do is send thoughts and prayers, then it's time for victims to be the change that we need to see. Since the time of the founding fathers and since they added the Second Amendment to the Constitution, our guns have developed at a rate that leaves me dizzy. The guns have changed, but our laws have not."

Gonzalez called out one of Trump's tweets following the shooting that left 17 people dead.

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"So many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behavior. Neighbors and classmates knew he was a big problem. Must always report such instances to authorities, again and again!" Trump wrote Thursday morning.

Gonzalez said Saturday: "We did, time and time again. Since he was in middle school, it was no surprise to anyone who knew him to hear that he was the shooter. Those talking about how we should have not ostracized him, you didn't know this kid, OK? We did. We know that they are claiming mental health issues, and I am not a psychologist, but we need to pay attention to the fact that this was not just a mental health issue. He would not have harmed that many students with a knife."

She added: "If the president wants to come up to me and tell me to my face that it was a terrible tragedy and how it should never have happened and maintain telling us how nothing is going to be done about it, I'm going to happily ask him how much money he received from the National Rifle Association."

She went on to criticize him and other lawmakers.

"To every politician who is taking donations from the NRA, shame on you!" she said, prompting the crowd to chant, "Shame on you" in response.

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"Politicians who sit in their gilded House and Senate seats funded by the NRA telling us nothing could have been done to prevent this, we call BS,” Gonzalez said. “They say tougher gun laws do not decrease gun violence. We call BS. They say a good guy with a gun stops a bad guy with a gun. We call BS. They say guns are just tools like knives and are as dangerous as cars. We call BS. They say no laws could have prevented the hundreds of senseless tragedies that have occurred. We call BS. That us kids don't know what we're talking about, that we're too young to understand how the government works. We call BS."