Part of the suit stems from the December 2007 shooting death of 14-year-old Vernon Eddins outside of Barnard-White Middle School.
Nobody has been arrested for that crime.
The lawsuit claims a Hispanic gang called the "Decotos" has targeted black youths for several years.
Eddins' mother, Alvette Fobbs, is one of the people suing Union City police and the New Haven Unified School District.
"Our kids are living a horror movie. They've had to live this life for three years. An innocent life has been taken, attempts on others, and still nothing is being done," says Fobbs.
"The Union City Police Department and the City of Union City have a long-standing record of being responsive to the supporting and defending the rights of all members of our diverse community," says police department Capt. Kevin Finnerty.
The plaintiffs also insist someone opened fire on a group of teens at Hayward's Southland Mall this past Saturday because they wore shirts honoring Eddins.