Two bicyclists died after being struck by a Jeep on the Rickenbacker Causeway Sunday afternoon, Miami Police said.
An adult male and adult female were struck and pronounced dead on the scene by Miami Fire Rescue.
"As soon as we heard it, saw it, we checked for pulse cause it was a super hard crash," one witness told NBC 6.
Witnesses say a number of people rushed to try to help, but the cyclists' injuries were too severe.
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"He ran them over...killed them instantly," witness Biagio Mazzeo said. "It's really, really sad."
Witnesses said there were multiple occupants in the Jeep when it struck both cyclists.
The driver of the Jeep has been detained for questioning, Miami Police said.
Cyclists said incidents like this have become common and they fear for their safety.
"It could happen to me, of course, I have been close to it," said bicyclist Brismel Oquendo.
The crash happened on the eastbound lanes of the causeway shutting down the roadway but it has since reopened.
The Rickenbacker Causeway connects Miami and Key Biscayne across Biscayne Bay.
This is a developing story, Check back with NBC 6 for updates.