The incident was reported about 12:15 p.m. Monday at a building in the 8800 block of Wilshire Boulevard, a commercial district, according to a statement from the Beverly Hills Police Department.
Witnesses told KTLA-TV that paparazzi were camped out outside the building as Kardashian arrived for an appointment. A man holding open the door was reportedly yelling racial slurs and other derogatory comments at the photographers.
When Kardashian asked him to stop, he allegedly directed his tirade toward her, according to law enforcement sources. Kardashian then apparently called West, who arrived a short time later. After she pointed out the offender, West attacked him, Michael Smith, who works in the building, told KTLA.
“It probably a little bit of an incredible reaction, but probably warranted," Smith said.
West, who police said was identified "by the victim and several witnesses," left the scene before officers arrived. Police did not identify the alleged victim.
Later in the day, Beverly Hills police announced that they had launched a battery investigation.
West pleaded not guilty in November to charges of battery and attempted grand theft in connection with a physical altercation at LAX with a paparazzo.