Same story, told with three different breeds:
It happened near 5th Ave and South 8th street. An elderly woman says she was outside training her own dog when a dog she describes as a boxer mix ran up to her and knocked her down. LINK
A dog from across the street approached, then attacked the woman and her pet. A Council Bluffs Animal Control official described the dog that attacked as an American Bull Dog. LINK
Loose pitbull stabbed to death following attack of dog walker - described as an American Bulldog in the actual article, though.
The woman was not harmed in any significant way. The dog was not harmed, either. The loose dog, who was licensed and vaccinated, was killed after being stabbed four times.
And yes, Council Bluffs has banned pit bulls.