A man in his 40s has been shot dead at the doorway of a home in Merrylands West, western Sydney, prompting a major police investigation. The shooting occurred on Wednesday afternoon, with emergency services unable to save the man at the scene.

Police believe the victim had arrived at the property shortly before the shooting with a male resident and two children. The children were reportedly inside the home when the shots were fired. Detectives are investigating whether the victim may have been mistakenly targeted.

Investigators are searching for a grey Audi sedan that was captured on CCTV leaving the area. Police are examining available footage and other evidence to establish who was responsible and determine the circumstances leading to the shooting.

The incident comes just a day after another fatal shooting in southwest Sydney, where a 23-year-old man was killed in his home. Police are examining whether the two shootings could be connected to organised-crime activity and possible mistaken identity.

Authorities have described the shootings as extremely dangerous because they occurred in residential areas where innocent members of the public could be placed at risk.

The investigation is ongoing, and police have not announced arrests in relation to the Merrylands West shooting. Detectives are continuing to gather evidence and establish the identities of those responsible.