The family of an 18-year-old apprentice who was killed when scaffolding collapsed at a Sydney construction site are calling for immediate changes within the industry.

Christopher Cassaniti was crushed to death on Monday after 15-metre high scaffolding collapsed on him and a co-worker at a construction site in Macquarie Park.

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"We feel devastated and empty by the loss of our beautiful boy Christopher," his family said in a statement on Tuesday.

I am just so saddened about the death of young scaffolding apprentice Christopher Cassaniti. To his parents and workmates my heart goes out to you. Just heartbreaking.

— Scott Morrison (@ScottMorrisonMP) April 1, 2019

Shocking and heartbreaking news from Sydney yesterday with the death of an 18 year old apprentice. As a father of 3, it is incomprehensible what his family must be going through at this time - and I think I speak for everyone when I say they are in our thoughts. — Bill Shorten (@billshortenmp) April 1, 2019

The family members said they didn't want the young tradesman's death to be "just another statistic".

"We ask that the government step in and take immediate action and implement stringent measures regarding safety on construction sites."

Paramedics were initially unable to reach the formworker who was trapped under rubble and was pronounced dead at the scene a few hours after the incident.

Video from the scene showed workers confronting police who refused to let them search the tangled metal at the apartment complex site.

0:00 One dead, another critically injured after scaffolding collapse 00:00 / 00:00 Share Share on Twitter

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"You're wasting time," one worker yells.

"If you move anything more, it could collapse," an officer responds, saying other emergency crews needed to stabilise the site.

Mr Cassaniti's family said no one else should have to endure the "horrendous pain" they faced as a result of the incident in which a second man received injuries to his lower body.

Days before his death, Mr Cassaniti's mother sung the praises of her son, who turned 18 on Wednesday.

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"We wish you all the best that the world can dish out and may God be forever in your heart and bless you with much joy, happiness and most importantly health," she posted to Facebook.

Friend Benjamin Betros said Mr Cassaniti had a "heart of gold".

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Another friend, Bella Mineo, said on Facebook: "You have been my friend since the first day of kindergarten ... words can't express how much this hurts. You were full of positivity, always smiling, always seeing the best in everyone."

Mr Cassaniti's death also prompted condolences from political leaders.

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"I am just so saddened about the death of young scaffolding apprentice Christopher Cassaniti. To his parents and workmates, my heart goes out to you," Prime Minister Scott Morrison tweeted on Tuesday morning.

Opposition leader Bill Shorten also sent his condolences and described Mr Cassaniti's death as shocking.

"As a father of three, it is incomprehensible what his family must be going through at this time - and I think I speak for everyone when I say they are in our thoughts," Mr Shorten tweeted.

A spokesman for construction company Ganellen expressed sympathy to the family, colleagues and friends of the young man.

SafeWork NSW and police are now trying to work out why the scaffolding at the Lachlan's Line apartment complex collapsed.