Talk to the hysterical man and get the scanner. Now head to the accident site and find the first package. Once you found it, zoom in with your camera and take a photo of it. This is pretty straight forward so you just need to follow the objective markers and search for the glowing packages in the blue search areas.
For the third package, you have to shoot the lock on the container van to find it inside.
The trickiest package is the last one, located behind the waterfall. To reach it, you may have to jump down to the river below and climb back up using the rocky outcrops.