Hunt for suspects as children fall in hail of gunfire

A mass shooting at an outdoor neighborhood block party in Baltimore, Maryland, left two people dead and 28 others injured - about half of them children - as police seek multiple suspects.

Authorities offered no motive for the gun violence, which erupted at about 12.35am local time in a courtyard between a pair of two-story rowhouses in South Baltimore's Brooklyn Homes community.

The two people slain in the hail of gunfire were identified by police as an 18-year-old woman and a 20-year-old man. Among the 28 survivors who were injured were an estimated 14 who were under the age of 18, added police.

The shooting likely ranks as Baltimore's largest single act of gun violence in terms of number of victims dating back to 2014, according to the Baltimore Sun newspaper.

Police were searching for multiple suspects.

A resident of the neighborhood said he was standing outside his home when he heard the crackle of gunfire, followed by a stampede of people fleeing in panic: "It was chaos. Parents were running around screaming looking for their children, not knowing if their child has a bullet in them."

One witness recounted hearing 20 to 30 gunshots.

The tragedy rattled Maryland's most populous city at the start of the Fourth of July weekend, a time when Americans typically gather to celebrate the holiday.