SAGINAW, Mich.—A 51-year-old woman and a 19-year-old man were slain and a dozen others wounded during a shooting at a large street party in Michigan that was promoted on social media.

The shooting occurred around midnight Saturday in Saginaw, about 102 miles (164 kilometers) northwest of Detroit, state police said.

Police initially said about 200 people were in the area of the party and that officers had been dispersing the crowd prior to the shooting, MLive.com reported.

Three people also were struck by cars and injured as people quickly fled from the gunshots, WNEM-TV reported. Investigators determined five different guns had been fired in the shooting.

No arrests were made.