Four suspected gang members arrested in last week’s fight at the Six Flags Magic Mountain amusement park have been released because none of the assault victims could identify them as their attackers, the Los Angeles County Sheriff’s Department said. A fifth arrestee, Samuel Trujillo, 18, of San Fernando, pleaded not guilty in Newhall Municipal Court to one felony count of assault with a deadly weapon. A preliminary hearing for Trujillo, who allegedly kicked a security guard in the head, is scheduled July 8. The fighting broke out early Friday morning between rival gangs from the San Fernando Valley. Four members of the park’s security force and six of the combatants were injured. Seven people were hospitalized, but all have been released.