Baseball fans who had gathered in downtown Los Angeles to celebrate the Dodgers' World Series victory threw projectiles and fireworks at officers who were attempting to disperse them, police said.
The "hostile" crowd, which had been gathered near 9th and Flower streets, was deemed an unlawful assembly late on Wednesday, the Los Angeles Police Department said on social media.
"Leave the area immediately and follow all officers orders," the department said on social media.
As police ordered the dispersal, the crowds began moving east, heading toward 8th Street, police said.
"Various projectiles are being thrown at LAPD Officers in the area of Olympic & Grand," the department added. "Extra resources are responding to that area to assist. If you are on the street, at or adjacent to that intersection, leave the area immediately & follow officers orders."
MORE: Los Angeles Dodgers win the 2024 World SeriesPolice said they had also received reports of looting nearby. The department's Central Division said in a statement posted on social media early Thursday that arrests had been made.
Mayor Karen Bass earlier had warned that "violence will not be tolerated" as the city celebrated its win over the New York Yankees.
"LAPD is currently on tactical alert and has activated a strategic plan to protect communities and businesses," she said, "which includes proactive deployment and a coordinated strategy with regional partners to ensure that all Angelenos are able to celebrate safely."