It happened before 9:00 a.m. Monday in Canby Park.
Police say William Blythe, Jr. was walking his 7-year-old terrier mix named Fitz when an 8-year-old American pit bull terrier named Paco began attacking Fitz, picking the smaller dog up by the neck and shaking it from side to side.
Paco, a resident of the Faithful Friends no-kill animal shelter in Wilmington for the last two years, was being walked in the park by shelter employee Lamotte Howard, 23, when the attack happened.
Police say Howard had let Paco off his leash to let him run in the park.
Police say Howard and Blythe tried unsuccessfully to separate the two dogs. Blythe then got the pit bull into a head lock, pulled out a .9mm handgun and shot the dog in the head. Paco died instantly.
Fitz was taken to a nearby animal hospital to be treated for his wounds. He is expected to recover.
Police cited Howard for allowing the dog to run loose off its leash. He faces a $250 fine.
The SPCA said Blythe will not be charged. Delaware law allows the killing of a dog if it is allowed to run free and attacks another dog that is under the immediate control of its owner.
Monday afternoon, Jane Pierantozzi, the Faithful Friends animal shelter's executive director, released the following statement:
Faithful Friends continues to investigate this morning's unfortunate incident, involving the injury of two dogs. While one of the dogs involved was a pit bull, we don't believe that to be the cause of the incident. Aggressive behavior can occur within any breed, resulting from genetics or the animal's personal experiences. Faithful Friends is a no-kill shelter that takes animal safety very seriously. We would never knowingly put any person or animal in danger.