A 65-year-old good Samaritan has died in hospital after he was allegedly assaulted trying to help a woman in Toowoomba.

Norman Olsen was driving with his partner in the suburb of Wilsonton on Monday when police say he saw a woman being attacked by a young man in an alleged domestic dispute.

The Vietnam veteran tried to intervene but was allegedly pushed to the ground by 22-year-old James Callow, who has since been charged with manslaughter.

Key points: Norman Olsen tried to help a woman who was allegedly being attacked on Monday

Norman Olsen tried to help a woman who was allegedly being attacked on Monday The 65-year-old Vietnam veteran hit his head on the road after allegedly being pushed

The 65-year-old Vietnam veteran hit his head on the road after allegedly being pushed He died in a Brisbane hospital on Tuesday

Mr Olsen hit his head on the road.

He was taken to Toowoomba Hospital with a serious head injury before being taken to Brisbane's Princess Alexandra Hospital, where he died late on Tuesday.

Detective Inspector Paul McCusker said Mr Olsen should be commended for his actions.

"He saw a person in distress and he's put himself in harm's way," he said.

"He has paid the ultimate price for that, and all I can is that it's a very courageous act."

Mr Olsen was in town to help one of his three daughters move house from Ipswich to Toowoomba.

Mr Olsen on his wedding day. ( Facebook: Manda Olsen-Hart )

One of his daughters, Manda Olsen-Hart, posted memories of Mr Olsen on her Facebook page.

"[You] were a fighter for many years but could not fight the serious brain injury you got from stepping in to help a bystander," she wrote.

"We had our ups and downs but u [sic] will never be forgotten."

Granddaughter Tiffany Olsen-Hart, 20, travelled up with her two-year-old daughter, who met Mr Olsen for the first time while he was on life support.

"It was a very special moment," she said.

"I haven't seen him for a few years but growing up I have great memory's [sic] of him like him taking me to my first day of school, him being at my birthday party's [sic] and when he came to stay with us in Melbourne."

Bridge Street in Toowoomba, where Mr Olsen was allegedly assaulted on Monday. ( ABC News: Casey Biggs )

Premier Annastacia Palaszczuk offered her sympathy to Mr Olsen's relatives.

"Stopping on the side of the road to provide assistance to a woman in distress, with tragic consequences, so my thoughts and prayers are with the family," she said.

"We've offered them all the support that we can at this time and we'll continue to support the family."

Callow appeared briefly in Toowoomba Magistrates Court on Tuesday, where the matter was adjourned until April.

He was initially charged with drug offences and grievous bodily harm, but that has been upgraded to manslaughter.