Three friends have had tattoos done in honour of a teenage boy who was tragically killed in a horror late-night jet ski accident.

Mitchell Irvine, 15, was killed and his friend, Noah, was critically injured when the jet ski they were riding crashed into an object in the Georges River near Tom Uglys bridge at Sylvania, in Sydney’s south, just after 6pm on Tuesday.

Noah, 14, was rescued and rushed to hospital with a severed arm, while Mitchell’s body was later found in the water.

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Dozens of devastated teenagers have paid tribute to Mitchell and have sent well wishes for Noah’s recovery as he remains in Sydney Children’s Hospital in a stable condition.

In one touching tribute, a friend shared a post on Wednesday night showing three mates posing with fresh ink on their arm.

The matching tattoos read “LLM”, an acronym for “Long Live Mitchell”, which friends have been frequently posting online in memory of the teen.

Friends have also set up a makeshift memorial near Tom Uglys bridge, featuring crosses, flowers, candles, and letters.

Photos posted online show the teenagers lighting candles and embracing at the memorial site on Wednesday.

Mitchell has been remembered as the “purest boy you could ever meet”, who had “many great friendships” with his mates.

“I’m going to miss you so much bro,” another friend wrote.

“Take care up there lad, 4eva (sic) 15.

“Won’t be the same without you here.”

“Forever in our hearts,” someone else said.

“We love you Mitch, LLM.”

The alarm was raised on Tuesday night when two girls contacted emergency services after hearing Noah in the river calling out for help.

Constable Jesse Hockey and paramedic Scott McNamara, who were among the first responders on scene, have been praised for their bravery after dashing into the water to save Noah.

“Both officers jumped into the water at night (in) very murky conditions, very scary (conditions),” Superintendent Don Faulds said on Wednesday.

“There was a lot of fuel in the water as well and (it was) unknown what else could have been in the water at the time.

“They raced out, secured the young person, (and) brought them safely back to the shore.

“From my perspective, (that is a) very, very brave effort.”

Faulds said the boys were riding on a jet ski owned by one of the families and that both teenagers were wearing lifebelts.

www.20304050.best understands the jet ski was owned by the Watkins family and that Noah had a licence to operate it.

Investigations into the crash continue.