Rewards:
This mission is received from an NPC in US Auto after liberating it. There are three locked container vans in the immediate area. The first prisoner is found inside a locked container van behind the garage. Destroy the lock to free him.
The farthest container near the hills has a bear inside. You still need to break the lock then kill the bear to find the mauled prisoner inside.
The last prisoner is trapped inside the restroom of the main office. Find the key on the counter beside a mug and use it to free the prisoner.