Mexican authorities recently recovered a large amount of ammunition that was stolen when two trucks were hijacked by armed assailants earlier this month.

The armed robbery occurred on June 9 in Guanajuato as gunmen targeted two trucks that had a picked up loads from an ammunition factory in Cuernavaca and were headed to a drop off point in Texas.

The trucks were recovered following the robbery, but the trailers had been emptied of about 7 million rounds of ammunition. Local media outlets estimate that the stolen ammunition was valued around $2.7 million.

More than 98% of the stolen rounds were .22 caliber sold in the U.S. under the Aguila brand.

Experts say that Mexican cartels rarely use such low-powered ammunition.

The truck drivers and security guards were later found unharmed.

Business Insider reports that the ammo heist was likely an inside job as the gunmen knew when the trucks would be passing and left the truck drivers and guards alive without either side firing on the other.

On June 17, Mexican authorities announced that they had recovered much of the stolen ammunition less than 20 miles from the site of the robbery in Guanajuato.

Approximately 5 million founds were found in “a dry box type trailer about to collapse loaded with boxes of useful cartridges … According to preliminary information, this is linked to the two trailers loaded with stolen weapons from Guanajuato,” Guardia Nacional said in a tweet.