Four people are in police custody after a 27-year-old man drowned at Hobart's waterfront after allegedly being pushed off a wharf during an attempt to steal a handbag.
A woman who was with the man raised the alarm after the pair ended up in the water at Princes Wharf around 10pm on Monday.
She managed to swim to a nearby ladder and climb to safety.
The man, who could not swim, was pulled from the water by police but was unable to be saved despite the efforts of paramedics and two passers-by who jumped in to help.
The pair were pushed from behind by a person who was trying to steal the woman's handbag, police say.
Two females, aged 17 and 25, were taken into custody by police in the northern Hobart suburb of Glenorchy on Tuesday afternoon.
After further searches, two males aged 17 and 19, were arrested at nearby Claremont.
Police investigations are continuing.
Detective Inspector David Gill said the man and woman were sitting near the edge of wharf talking.
"This ... act has resulted in a terrible tragedy," he said.
"A tragedy that will haunt the young (woman) for the rest of her life, along with the family and friends of the (man) and the two members of the public and officers (who responded)."
Det Insp Gill said police were in the process of notifying next of kin and couldn't yet provide further details about the victim.
"I would like to recognise the heroic efforts of the passing members of the public who entered the water in an attempt to rescue the man (and the) outstanding efforts of our responding police and emergency service personnel under very difficult circumstances," he said.
There was no evidence alcohol played a role in the man's inability to swim, Det Insp Gill said.
Police divers have searched for the handbag, which has yet to be found.
Princes Wharf is a short walk from the Hobart CBD and features restaurants and bars.
Two Victorian men have died in separate incidents at the city's waterfront in recent years after falling into the water.
Dr Robert Bo Xu drowned in November 2019 and Jarrod Robert Davies, who was visiting Tasmania with his father, drowned in February 2020.
A coronial inquest into their deaths, which is yet to deliver findings, has been told both men had consumed a considerable amount of alcohol.
