FLORIDA, United States – Four Florida men were arrested for installing devices inside gas pumps that dropped prices down to nearly nothing, according to reports.

In an alarming trend that officials said will only spread with fuel costs soaring, the Florida Department of Agriculture and Consumer Services said the suspects installed sophisticated “pulsators” inside pumps that regulate price and fuel flow.

According to the New York Post article, the devices sent per-gallon cost plunging down to just pennies and allowed pumpers to fill up almost for free.

Rogelio Llerena and Yulier Garcia-Martinez were busted on March 12 while topping off an oversize gas tank in Lakeland. Yordian Diaz-Benitez, of Tampa, was arrested at a Lutz station for stealing diesel fuel on March 10. Marlon Rosel-Rodriguez was cuffed two days later for attempting to place the device inside a pump at the same station.

“Law enforcement agencies have warned station owners to look out for trucks stopped at pumps for unusually long periods. Worried station clerks are also cross-checking their inventory outflow and income to check for hacked pumps,” the NY Post read.