A man who is fighting for life after a horror worksite accident that killed his colleague has been left paralysed and with punctured lungs.

Aymen Alahmad, 30, and Paulo Mau’u, 40, suffered critical injuries at a Meriton construction site on Pennant Hills Rd, near Shirley St, in Carlingford, in Sydney’s northwest, about 9am on Tuesday.

Mau’u was taken to Westmead Hospital, where he later died.

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Alahmad was taken to Royal North Shore Hospital, where he remains in a critical condition fighting for life.

It is believed the men were injured by concrete pumping equipment.

Loved one Abdullah Malas has revealed Alahmad requires a “critical” and “very delicate” operation on his spine.

“Aymen is a devoted father to three young girls and a loving husband and a son a mother relies on,” Malas said.

As Alahmad’s family brace for his long road to recovery, Malas has launched a GoFundMe to help them.

“He’s always been the one to provide for his family, working hard in the field, and now it’s our turn to come together to support him and his loved ones,” Malas said.

“Aymen is the kind of person who would do anything to help others, and now we want to show him the same kindness and generosity he’s always shown ... to provide as much support as possible to help Aymen focus on his recovery and his family focus on healing.”

Meanwhile, tributes have begun pouring in for Mau’u as devastated loved ones urge others to “never take life for granted”.

“We never really know when the last time you see someone is the ‘last time’,” one friend said.

“RIP ma uso (Samoan for ‘my brother’). Couldn’t believe the news, will forever miss your good vibes and energy.

“Love ya ma uso. You truly will be missed.”

“Rest in peace brother,” another friend wrote. “I’m really hurt. Never forget you.”

According to his social media profiles, Mau’u was a “proud Samoan” who migrated to Australia from New Zealand.

Meriton on Tuesday said the company was “devastated” by what had happened.

“Our hearts go out to their families, friends, and colleagues during this incredibly difficult time,” it said.

“We extend our deepest condolences and stand with them in their grief and pain.”

Meriton said safety at its construction sites was its highest priority and it was “co-operating fully” with SafeWork NSW.

Police are investigating and the incident has been referred to SafeWork NSW.

There was another incident at the same worksite in June when roads were closed due to an unstable crane.

One or two of the crane’s two anchor pins had failed, causing it to tilt at the base.

At least 350 workers and nearby residents were evacuated as a precaution.

No one was injured.