A 38-year-old man was allegedly set upon by a group of men dressed in black as he waited for the lights on Princess St to turn green.
He had driven past a funeral on Main St and, as he approached the lights, a black custom van has pulled in behind him.
A witness told the Manawatu Guardian she saw at least six men leap from the van and start attacking the victim's vehicle, a red and black Falcon ute, with aluminium baseball bats.
"They smashed it up, all the windows, and dragged the guy out. They hit the kid who was in the passenger seat and the two dogs were also in the cab.
"They must have damaged the door because the poor kid was trying to get it open, he was holding his arm and you could see a huge black mark, like a bruise that had come up immediately."
The two dogs inside the canopy managed to get out but were then set upon by one of the men. The witness said one dog was hit several times across the head and neck.
"I thought they were going to kill that dog."
Several people had gathered on the streets but no one helped, she said.
"There were people gathered all over, big guys too, but no one helped. The father was on the ground and they were just hammering him. The side of his face was caved in, he was covered in blood."
She said once the men had finished the attack, they looked at one another and got back in the van.
"They did a u-turn and went back down Main St. They had come from the funeral up the road and they went back that way. There were people from the funeral watching this from the Cobb across the road.
"These men didn't have their faces covered and they didn't care who was watching. These men were all in black, were well groomed, they were spic-and-span looking."
The woman said the father appeared dazed and confused after the attack.
"He was on the ground and saying he couldn't breathe. He was just saying, 'f***, f***, what the f*** man, I was just driving past the funeral then I had these guys up my ass'."
She also said a group of motorcyclists drove past the scene within minutes of the van leaving, "pulling the fingers".
"I think this was a gang-on-gang thing."
The father and son were taken to hospital but have since been discharged.
The dog also received veterinary attention for bruising.
At the time of the assault, police said they were sickened any adult males would set upon a young boy.
Anyone with information was asked to call Central District Police on (06) 351 3781 or call the anonymous Crimestoppers line on 0800 555 111.