Police are investigating a case of theft after three coin security guards were robbed in Jet Park on the East Rand, police said on Tuesday.

Spokesperson Tsietsi Lamola said a manager at coin security sent someone to investigate why one of his vehicles was involved in an accident on Monday night.

"Upon arrival, his employee found the three guards inside the cash van who appeared to be intoxicated as they could not explain what happened or where they were," said Lamola.

"The van was opened and an undisclosed amount of cash was stolen from the van. The circumstances on how it happened [are] still under investigation."

Anyone with information can contact the Boksburg north detective branch on 011 898 3009/3000.