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 on 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 on 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.
No one has been taken into custody and police were urging witnesses to come forward.
Wilkinsburg is located around 10 kilometres (six miles) east of the city of Pittsburgh.
Police said shots were fired from an alley and that when party-goers 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.
According to CBS affiliate KDKA, neighbours reported hearing 30 to 40 shots ring out.
Emergency dispatchers said seven ambulances were called to the scene, according to local broadcaster WPXI.
Neighbourhood resident Kayla Alexander told WPXI that the street where the shooting occurred is normally quiet and filled with playing children.
Local media footage from the scene showed a massive police presence and streets blocked off as visibly distraught groups of onlookers wept and hugged.
WPXI reported that some said they had lost family members.
The rampage represents the latest mass shooting to rock the United States, where such attacks have become commonplace.
Late last month, a factory worker killed three people and wounded 17 in a shooting spree in Kansas.
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.