Since the incident, at 9.30pm last Thursday, the dog has been seized and police have arrested two men.
Residents in the quiet cul-de-sac say they fear it could happen again.
"The idea of a dog attacking a person in this area is not a very nice thought."
A dog walker from the area, who also wanted to remain anonymous, added: "I'm a dog lover, but there's something about pit bulls I just don't trust. I hope the man recovers soon."
Another resident said: "I'm shocked about it, most people are – this is normally a safe area
"I worry it could happen again unless the police do something with the owners."
Police raided a house in Norman Ball Way and searched for suspected fighting dogs under the Dangerous Dogs Act.
A pit bull-type dog was confiscated, and an 18-year-old man was arrested on suspicion of conspiracy to cause grievous bodily harm.
A 24-year-old Gloucester man was also arrested on suspicion of causing grievous bodily harm.
Gloucestershire Police's Mark Duncton, Sergeant of the constabulary dog section, said: "Owning, possessing and breeding of prohibited dogs is illegal and constitutes a risk to public safety.
"I hope this operation shows that we will take action to implement enforcement measures if required, and keep our communities safe."
The dog will now be assessed in secure kennels.
City councillor Sebastian Field (Lib Dem, Kingsholm and Wotton) said: "Obviously it's not the sort of incident I would expect down there, so it has somewhat come out of the blue. It is a bit of a shock to hear about it."
Anyone with information about the incident should call Gloucestershire Police on 0845 090 1234, quoting incident 466 of January 20.
Alternatively, anyone can call Crimestoppers anonymously on 0800 555 111.
Pit bulls are popular, with many websites springing about how to nurture them, but they have been linked with illegal dog fighting events.