At least two people were killed and 28 wounded in a mass shooting at a street party early Sunday in the US city of Baltimore, police said.

Police received multiple calls about a shooting in the city's Brooklyn neighborhood just after 12:30 am Sunday (0430 GMT), Acting Police Commissioner Rich Worley told a press conference.

"Upon officers' arrival we located multiple victims suffering from gunshot wounds," Worley said.

One 18-year-old woman was found dead at the scene in the East Coast port city, and a 20-year-old man died after being taken to hospital, a police statement said.

The wounded were being treated at area hospitals, he added, with three of them in critical condition.

Worley said authorities were working to identify a suspect and determine a motive for the shooting.

"This is an extensive crime scene, our detectives are going to be here quite a while," he said.

Baltimore Mayor Brandon Scott, speaking to reporters at the crime scene, condemned the shooting.

"This is an absolute tragedy that did not have to happen," he said.

"It again highlights the impacts and the need to deal with the over-proliferation of illegal guns on our streets and the ability for those who should not have them to get their hands on them," Scott said.

"We will not stop until we find those cowards who decided to just shoot dozens of people, causing two people to lose their lives," he said.

- 'Countless' ways to reduce violence -

With more firearms than inhabitants, the United States has the highest rate of gun deaths of any developed country -- at least 44,357 in 2022, including 24,090 suicides, according to the Gun Violence Archive (GVA).

Sunday's incident was at least the 338th mass shooting to occur so far this year, according to the GVA, which defines the term as a gun-related incident in which four or more people are wounded or killed.

Earlier this year, Scott penned an editorial in The Washington Post in which he said his city "has over-relied on the three Ps -- policing, prosecution and prisons -- to reduce violence."

"An act of violence doesn't start or end when someone pulls a trigger. There are countless points along the way where we can intervene," wrote the mayor, who was elected in 2020 on a pledge to reduce gun violence.

That includes access to "behavioral health services, housing support, life coaching, case management and other resources to ensure that a situation never gets to the moment at which a person harms another human being."

Baltimore, a city of about 575,000 located 40 miles (65 kilometers) north of the US capital, has one of the highest murder rates in the country.