Read through the wiki page you linked.
Prisoners weren't all taken at the same time (if I understood it properly, was more skimming than reading). In the end it was three who surrendered, one of the conditions being medical aid for a lieutenant.
The rest were captured over the course of the fighting (if, again, I understood properly).
Tho yeah, still an interesting battle.
EDIT - Also they were given multiple chances to surrender, they refused all but the last one. So it isn't like they immediately just dropped their weapons, they did fight a lot first.