Officers from through Taranaki were called in after about 60 Mongrel Mob and Black Power members armed with baseball bats, tomahawks and machetes clashed.
The drama began after the Mongrel Mob members stopped in Patea, 28km from Hawera, to refuel as they made their way from Hawke's Bay to Taranaki -- considered Black Power territory.
By the time they reached the southern boundary of Hawera a large group of Black Power members were waiting for them, and violence erupted.
The rioting stopped when the Mongrel Mob members were escorted out of town, Sergeant Jeremy Bull said.
He said he did not expect there to be further tensions but police would be monitoring the situation.
The violence was witnessed by Hawera motel manager Beth Martin.
"All of a sudden everything just blew up on South Rd -- we and our motel guests were terrified," she told the Taranaki Daily News.
"People were running everywhere with everything from baseball bats to axes. There was incredible shouting and abuse, and cars were getting bashed. We dialled 111 and were told to stay in our buildings and lock the doors.
"We dived indoors and stayed there. I've never, ever seen anything like it -- I'm still shaking," Mrs Martin said.
