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Semel, 28, daughter of former Yahoo! CEO Terry Semel and star of E!'s Filthy Rich: Cattle Drive, was not arrested, but she must pay a fine or face a Las Vegas justice court judge.
Las Vegas Metro Police Officer Jay Rivera tells PEOPLE that Semel "struck a hotel security guard in the back of the head" during an altercation at 4 a.m. Wednesday.
A source says Semel, a former friend of Lindsay Lohan and the 26-year-old Tequila's current girlfriend, was at Caesars Palace's Pure Nightclub that evening and left her cell phone on the property. When she went back to retrieve it, the club was closed.
"She demanded that they find [the phone] and hit the security guard," the source says.
The hotel security guard did not suffer any injuries, Rivera says, adding that Semel was detained in the Caesars Palace's security office until Metro police arrived.
"She was cited for battery and released," Rivera said.
The incident occurred after Semel attended an event hosted by BestofVegas.com at Palazzo Las Vegas's Sushi Samba with both Nicky Hilton and Kourtney Kardashian.
Tequila's rep could not be reached for comment.
