Udo Bühler, spokesman for the Hessian state police, told the website of daily Die Welt on Thursday that several suspects showed up at the main police station.
The wounded man, a 31-year-old from Wiesbaden, who has been kept under police guard since the shooting on Tuesday evening, will be questioned by a bail judge on Thursday afternoon.
Two men aged 28 and 49 were arrested on Tuesday night, but the level of their alleged involvement is not yet clear.
A special investigation team has been established to delve into the background of the case, which is said to have started last weekend in front of a club in Mainz. It is thought to have been caused by a case of injured pride.
Investigators have told journalists that all those thought to have been involved are of Turkish background.
It seems four or five men attacked a group of three or four men sitting at a table in the ice cream parlour in Rüsselsheim and that at least one gun and several knives were used during the ensuing fight.
One of the dead men, as well as the injured man are said to be 26- and 31-year-old brothers, and to have been part of the attacking group. The other dead man is a 29-year-old from Raunheim.
The third victim was a 55-year-old Greek woman who was sitting drinking a coffee in the next-door restaurant and had nothing to do with the fight. She was hit by a bullet in the stomach and died at the scene.