Two "barra brava" hooligans riding a motorbike took 10 to 12 shots at a rival faction of Newell's fans and officer Maximo Alegre was hit in the buttocks, the local newspaper La Capital said. His life was not in danger.
Police chief Cristian Sola of Rosario, 300 km north of Buenos Aires, and the Security Secretary for Santa Fe province, Horacio Ghirardi, announced the decision to suspend the match at the Marcelo Bielsa stadium.
It was the third match suspended due to violence among fans in the 19-round Clausura, second of two championships in the season.
Velez Sarsfield's home match against San Lorenzo in March was suspended after just seven minutes when a Saints fan died after fighting between fans and police.
The remaining 83 minutes were played a month later with Velez winning 2-0.
Two weeks ago, champions Estudiantes were leading 2-0 at Huracan when home fans rioted in the stands.
The match was suspended in the 32nd minute and the rest of it was played behind closed doors on Thursday with Estudiantes winning 3-0.
Violence is endemic in Argentine football and turf wars between rival factions of fans of the same team have become more common than fighting against supporters of other sides.
In two matches on Monday involving teams at the front of the title race, leaders Velez are at home to third-placed Godoy Cruz while Lanus, who are second, visit Independiente. Fourth-placed Olimpo lost 2-0 at Arsenal on Friday.
