Vandals painted a large swastika on a soccer field at a Jewish-owned recreation center in Northridge and painted obscenities on walls throughout the complex, police said Wednesday.
Police had no suspects but said they were investigating the case as a possible hate crime.
The vandals painted a 5-foot-diameter swastika on the field turf and a smaller one on a wall.
"I don't know if it's a hate crime or it's just someone being stupid," said Ron Dennis, co-owner of Northridge Arena Soccer League on Shirley Avenue.
One swastika, he said "was done correctly, and one was backward. If it was really a hate crime, they would have known what they were doing."
Between 11:30 p.m. Tuesday and 11 a.m. Wednesday, the vandals hopped two fences and cut through goal nets to enter the outdoor arena, authorities said.
"They tore up some of the artificial turf. It weighs a lot, so it would take a few people to do it," Dennis said.
The obscene language was neatly printed, "almost like they used a stencil," arena manager J.D. Rotteau said.
Damage was estimated at $10,000.
Five games went on as scheduled Wednesday night.
About 40 games are played weekly in the arena's all-adult league.
Dennis said he was mystified about who might have done the damage.
"We've had no problems," he said. "This is a place you go to so you can get away from problems."