he must have stumbled.

In Salem, Oregon, a rapist attacked a 22-year-old woman on crutches. A car full of good Samaritans stopped when they saw what was happening, and proceeded to, uhm, intervene.

The article says that the good guys "pulled [the rapist] off the woman and held him until police arrived."

From his booking photo it looks like they did a bit more than just "pull him off" his intended victim.

(Nelson voice) "Ha ha!"