"We struggled for quite a few minutes before the dog let go, but we were trying not to aggravate it any more or cause any more damage."
He said the woman who was attacked had a small "fluffy" dog with her but the dog that had latched on to her had a strong build.
When it let go, Loh put pressure on the woman's injury and dressed it with items from the chemist.
"The first thing to do was to keep her safe and ourselves safe."
He said the woman had remained calm throughout the incident.
A police spokeswoman said they were notified of an incident involving an animal and were speaking to the informant about what happened.
St John did not attend.