Officials say one of the suspects was apprehended earlier today following a tip-off.
The US govt wants two SA brothers extradited for trying to sell rhino horns to American hunters.
The Czech Republic has become a major transit point for rhino horn trafficking in recent years.
At least 736 rhino have been killed in South Africa this year alone.
SANParks has missed the window to move rhino this year but has developed an alternative plan.
Police said officials recovered an unlicensed firearm as well as a rhino horn.