His staff member received injuries to his groin, while another man standing outside the bar received injuries to his hand. Both remain in Hawke's Bay Hospital in a stable condition.
Two men have since been arrested and are assisting police with their inquiries, but no charges have been filed at this stage.
Sunday's incident was believed to have stemmed from an earlier altercation between rival gangs who were in the West Quay Area in Ahuriri overnight, police said.
Sullivan said there were “a lot of people” in the area after 11pm and the bar was “very busy”, following on from a concert in Hastings.