A fight erupted Sunday afternoon at a normally quiet Ventura park, sending dozens of people running for cover from gunfire and flying rocks.
One youth was reported to be injured in the incident, and police detained one man for questioning.
An argument between two groups believed to be rival gangs apparently sparked the violence, which broke out around 5 p.m. at Hobert Park near Petit Avenue and Telegraph Road, police said.
Witnesses said they heard as many as four shots fired during the melee, touching off panic among the 80 to 100 people who were at the park. Witnesses also reported the two groups throwing rocks at each other.
One man was apparently beaten during the incident and taken by friends to a local hospital for treatment. As of 7 p.m., however, police could not locate the man, who police believe was beaten with a tire iron or baseball bat. No other injuries were reported.
A man who police would not identify was detained on suspicion of committing assault with a deadly weapon.
"Right now, we don't have a victim and without a victim we might not have a crime to charge our suspect," Ventura Police Capt. Randy Adams said. "We believe shots were fired here, but other than through witness accounts, we've found no physical evidence yet. So far, we haven't found any guns or even shell casings."
But according to Joanna Hernandez, 31, who was in the park to celebrate a birthday, the fighting and shooting caused widespread confusion.
"When the shots rang out, everyone either hit the ground or ran," she said. "I don't think it was a full-on gang fight. I just think it started by someone saying something to someone else that he didn't like."
Police were investigating whether the two groups gathered at the tree-lined park were gang members from Saticoy and Santa Paula.