The dog, whose owner has yet to be identified, attacked people at Duc Yen Primary and Secondary School in Dam Ha District in the northern province of Quang Ninh on Wednesday.
All victims were taken care of medically and are now in stable condition, while the dog was captured and later tested positive for rabies.
Quang Ninh Center for Disease Control and Prevention has not recorded any rabies cases in humans this year even though over 480 people have received vaccines due to their exposure to three rabid dog clusters in the province.
"The clusters are now under control. All who were exposed to them have been vaccinated and are being monitored," the center said.
Dam Ha District authorities have committed to vaccinate all dogs and cats in the area in the upcoming days.