Action News recorded the last few seconds of the fight just before sheriff's deputies broke it up.
They arrested 26-year-old Serena Jimenez for battery and an outstanding warrant.
Deputies say she was standing in line, waiting to attend a sentencing hearing in the courthouse, when she got into an argument with a woman from the opposing family. They say Jimenez threw a punch at the woman, but missed and hit her 64-year-old grandmother. Jimenez lost her top during the fight.
Deputies detained both women, but only arrested Jimenez.