Three people, including a child, have been arrested in relation to the public assassination of a suspected Sydney underworld figure in Vietnam last week.

The man, woman and child were bound for Auckland when they were arrested at Faleolo International Airport in Samoa on Thursday.

The man is wanted for questioning in relation to the gangland hit on Lorenzo Lemalu, and the suspected organising of two men to carry out the hit.

Lamalu, 24, was shot dead at a restaurant in Ho Chi Minh City last Thursday night, with CCTV showing a gunman open fire at Lamalu and another man on a footpath in front of horrified onlookers.

Lamalu’s associate, who was identified by local media as Sam Sauni, 27, was critically injured in the attack.

Lamalu is believed to be the mastermind behind a Sydney criminal organisation, colloquially known as the “Coconut Cartel”, which declared war on the rival Alameddine gang earlier this year.

No charges have been laid.

Lorenzo Lemalu was shot dead outside a restaurant in Vietnam last Thursday.Lorenzo Lemalu was shot dead outside a restaurant in Vietnam last Thursday. Credit: 7NEWS

The Samoan Central Bank had earlier ordered banks to “freeze without delay” all accounts linked to six individuals following a request from the Samoa Police and the Transnational Crime Unit in relation to investigations connected to the alleged gangland murder.

The six individuals named in the order are Tafia Tovia (also known as Steve Tafia), Vaa Soloa Vaa (also known as Vaa Vaa), Connor Songkran Strickert, Fred Olivia Junior Papalii, Olini Atiua and James Tuisavailuu Atua.

Unalei Car Rentals has been identified as the “associated entity” linked to the investigation.

It comes days after Vaa Vaa and Tafia confessed on national television in Vietnam to carrying out the hit under orders of a foreign “boss”.

Tofa and Va’a were arrested in Ho Chi Minh City on Tuesday in connection with the alleged murder, however it is believed they are to be charged.

The two men are believed to be Samoan nationals, with the Department of Foreign Affairs and Trade (DFAT) confirming they are not Australian citizens.

It has been alleged the two men were arrested by Vietnamese authorities while attempting to flee the country into Cambodia.

7NEWS understands the pair travelled to Vietnam using fake passports and names; Lang Kenny Trong Minh Do and Justin John White.

Australian Federal Police are working with Vietnamese authorities as investigations into the shooting continue.