Police believe the incident, which took place on Saturday at around 9pm local time (1am GMT), may have been sparked by an “exchange of words” between party-goers and a bystander who had approached the group.
The bystander then proceeded to open fire on the dozen people attending the party at an apartment complex in Camp Springs, Maryland, leaving three people with serious injuries and four more with minor injuries.
Officers from the Prince George’s State police department confirmed those who were seriously injured were in a stable condition following the incident.
Prince George’s County Police Chief Hank Stawinski said: “There were approximately a dozen people in attendance, and at one point an individual approached this group.
“There may have been words exchanged, but shortly thereafter a number of shots were fired into the party goers”.
All of those who suffered gunshot wounds were adults, with ages ranging from 18 to 20. They are all expected to survive their injuries.
The shooter, who is believed to have acted alone, is yet to be apprehended by police.
There have been more mass shootings across the US in 2019 then there have been days in the year so far – with at least 270 incidents taking place across 237 days according to data compiled by non-profit group the Gun Violence Archive.
In total there has been at least 36,498 gun related incidents, leading to more than 9,600 deaths and 19,100 injuries.