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Los Angeles law enforcement officials said on Monday morning they were investigating the singer Chris Brown for his possible involvement in an assault that occurred in West Hollywood on Sunday night.

The Los Angeles County Sheriff’s Department said in a statement reported by The Associated Press that it was looking into an incident that occurred outside the Westlake Recording Studios where witnesses said that six men had been involved in a fight over a parking space. “The altercation allegedly led to Chris Brown punching the victim,” the statement said.

The celebrity Web site TMZ.com reported that the unnamed victim referred to in the statement was the singer Frank Ocean. Mr. Ocean, who is up for six awards at the Grammys next month, wrote on his Twitter account: “got jumped by chris and a couple guys. lol.” In another post, he added: “cut my finger now I can’t play w two hands at the grammys.”

Mr. Brown, a fellow Grammy nominee, was arrested after the 2009 ceremony for attacking the singer Rihanna during an argument in their car on the night of the show. He later pleaded guilty to one felony count of assault and was sentenced to five years of probation and six months of community labor. Last summer, he was involved in a brawl at a New York club where he feuded with the rapper Drake. In November Mr. Brown temporarily shut down his Twitter account after an online war of words with the comedian Jenny Johnson.

Representatives for Mr. Brown and Mr. Ocean have not immediately commented on Monday’s police investigation.