Police say they are "sick and tired" of gun violence in Sydney after another shooting in the city's west overnight left four men in hospital.

The men were standing outside a house on The Horsely Drive at Smithfield when they were shot around 8.00pm (AEST).

More than a dozen bullet holes riddled a garage door at the property.

The victims, who are aged between 20 and 25, were taken to hospital with multiple gunshot wounds to their legs, and one man suffered a bullet wound to the stomach.

Police say the injured men are known to them, but they do not appear to have any links to bikie gangs.

However, officers say it appears to have been a targeted attack.

Superintendent Peter Lennon says the local community is fed up with gun violence.

"The police and the community of Fairfield are absolutely disgusted by what's taken place here," he said.

"We're sick and tired of what's happening in our area and we're trying to put a stop to it."

He says police are investigating the incident.

"We're not sure exactly what caused it," he said.

"I'm aware that there were SMS [text messages] sent out, and I know that other persons arrived by car, by foot, or by motorcycle."

Local resident Liliana says this sort of violence is extremely unusual for the area.

"Everything was just so nice and quiet, we were all friends, nothing like this has ever happened here. Ever. It's totally disgusting, honestly," she said.