A shooting at a backyard barbecue in a town in the northeastern US state of Pennsylvania has left five dead, with at least two suspects still on the run.

A shooting at a backyard barbecue in a town in the northeastern US state of Pennsylvania has left five dead, with at least two suspects still on the run, police said Thursday.

Four of the victims -- three women and one man -- died at the scene while another woman died in hospital, police said in a statement.

Two men are in critical condition and a woman is in stable condition following the incident that unfolded at a home late Wednesday in the town of Wilkinsburg, they said.

"The ballistic evidence on the scene leads police to believe that two different weapons were discharged from two different people," the statement said.

Wilkinsburg is located around 10 kilometers (six miles) east of the city of Pittsburgh.

Police said shots were fired from an alley and that when partygoers tried to seek cover in the home, someone on the side or backyard adjacent to the residence fired at the back porch, where all four deaths occurred.

No ages or identities of the victims has been released.

Other recent mass shootings include a rampage by an Uber driver that left six people dead in Michigan and the December terror attack in San Bernardino, California, in which 14 people lost their lives.

Gun violence is responsible for some 30,000 deaths per year in the country, with 330 mass shooting incidents recorded last year.