You saw as the centaur noticed the carrot you had planted in front of the railroad, and heard him gallop over to it, while it was making sure that there were no trains coming. You, and the sheriff hid behind the wall you were hiding behind, so you wouldn't get caught by the centaur, while at the same time hope that he takes the bait.
Just when you thought that the centaur might be onto you, while you remained hidden, you heard the sounds of the creature eating, while at the same time you knew it didn't stop. This was your chance, so you grab the net trap, and throw it over the centaur while it was distracted, and also closed all corners once it was caught. The centaur began to struggle, while trying to escape, but the sheriff pulled out a dart gun, that caused the centaur to become unconscious. "Job done," she says. "Now let's head back to Open Gulch."