It happened at around 1 a.m. near Sunset Boulevard and Larrabee Street.
According to the Los Angeles County Sheriff's Department, deputies spoke with a man and a woman who said they had been robbed by a group of men seen driving a black Rolls-Royce vehicle.
The woman told deputies the suspects approached them while they were in their car after an altercation in a nearby parking lot.
Investigators said the suspects stole one watch from the woman and another from the man.
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The watches were described by the woman as a Michael Kors watch valued at $1,000 and a Rolex worth $18,000, according to the sheriff's department.
The suspects reportedly got in a dark-colored Rolls-Royce and were last seen going southbound toward Larrabee Street.
They were described as a group of about four to six males wearing dark clothing.
"The victims did not know the suspects prior to the robbery," said the sheriff's department in a statement released Sunday afternoon.
The sheriff's department adds that both victims appeared to have been under the influence of alcohol and were "verbally and physically" uncooperative during the part of the investigation.
Anyone with information is urged to call the West Hollywood Station at 310-855-8850.