"The victim was then struck on the face a number of times and had his schoolbag taken."
The offenders were described as being between 16 and 25 years old.
The victim suffered a broken nose, fractured eye socket, cuts to his mouth and bruising.
This month, a taxi driver was assaulted in central Henderson about 4am and his wrist slashed by a teen with a broken bottle.
Stephanie Moore, 22, who works across the road from Mr Kumar's Railside Dairy, said the murder felt like the breaking point.
"To be honest, I'm not shocked. I'm shocked it was him, but I'm not shocked at what's going on.
"It's just the youth of today. Something needs to be done.
"In the two years I've been working here I've just seen Henderson, and West Auckland in general, it's plummeted. It's dangerous, no one is safe."
Fiza Mohammed, 39, said there was such a problem with youths on the streets she didn't want to walk home any more.
Shopkeepers in stores neighbouring Mr Kumar's said they were scared following the stabbing.
Area Commander Inspector Rob Cochrane said police had been focusing attention on central Henderson since November, doing daily patrols.
"The feedback that we've been getting, up until [Mr Kumar's murder], was people were feeling a lot safer than they had been."
People needed to report the problems so police could deal with them, he said: "If people feel unsafe, they need to call us."
