A 43-year-old Dunlop woman was stabbed in the chest about 7.50pm and died in hospital shortly afterwards.

Police have charged a 35-year-old Charnwood woman with murder. She is expected to appear in the ACT Magistrates Court on Monday morning.

A man who was a short distance from the incident, who didn't want to be named, said two couples were involved, one in their 40s and the other in their 20s or early 30s.

A fight had first begun between the two women.

''[Then] I saw the blokes having a bit of a punch up, and next thing there was a lot of screaming and apparently one girl had stabbed the other girl.''

He said the screaming had come from the woman's seven-year-old daughter, who witnessed the stabbing. Somebody had removed the girl shortly afterwards.

The woman lay where she was stabbed until the ambulance arrived shortly afterwards.

The woman who was stabbed had been gentle, polite, ''and seemed to be a good mother''. He had seen her at Charnwood shops almost every day for about two years.

He said the shopping centre, where the incident occurred, had been crowded, and ''40 or 50 people'' would have witnessed the stabbing.

Specialist response and security officers were searching the Charnwood shopping centre area for the weapon yesterday, which they suspected was a knife.

Officers have obtained security camera footage and are continuing investigations.

Meanwhile, police are also investigating a separate incident, which left a man in a serious condition in hospital on Friday.

The alleged victim was found about 5.30pm bleeding from a head wound after an assault in a flat at Reid.

Police arrested two men shortly after the incident.

Police are urging any witnesses to either of these incidents, who they have not yet spoken with, to contact Crime Stoppers on 1800333000 or via the website at www.act.crimestoppers.com.au