The mission begins with a cutscene in Ken's office speaking with the property developer, Avery Carrington. He asks you to handle a small company, Spand Express, to gain the prime development land.
The first instruction is to head to Rafael's clothes shop to gain a worker disguise, but this is optional. You can head directly to the company to do your task.
Drive to the company, and start a riot by attacking at least four workers - it's easiest to use a vehicle to run a few of them over. This will cause the security guards to open the gate and open fire. You can now run in, and shoot the gas canister to destroy two of the trucks. To destroy the third, you need to enter it and park it close to a second gas canister before shooting it. The mission will end as soon as all trucks are destroyed - and you will also receive a call from Colonel Garcia Cortez for a new mission.
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If you missed destroying one of the trucks, you can drive it out of the compound and attempt to destroy it by careless driving. A maneuver that rolls it upside down works perfectly.