Police Saturday warned drivers and pedestrians to avoid the downtown Los Angeles area after demonstrators closed all lanes of traffic on Alameda Avenue between Temple and Aliso streets.

After hundreds gathered in downtown LA for a “No Kings” protest, a large crowd of people began marching through the area mostly in peaceful manner.

But some protesters began gathering in front of the federal building, leading federal authorities to deploy tear gas on Alameda between Aliso and Temple.

As metal fencing was set up around the federal building, federal authorities said some demonstrators began throwing large concrete blocks, bottles and other objects over the fence.

First Assistant U.S. Attorney Bill Essayli said he authorized “immediate arrest” for those who assault law enforcement, planning to charge them with a federal felony.

PSA: My office has authorized immediate arrests for anyone assaulting law enforcement. You will be arrested and charged with a federal felony. https://t.co/vXolzw20le

— F.A. United States Attorney Bill Essayli (@USAttyEssayli) March 29, 2026

The Los Angeles Police Department said there were “acts of vandalism” being reported in the same area.

While the LAPD said it’s not involved with crowd management, it issued a tactical alert for the city of Los Angeles, followed by a dispersal order to everyone gathered in the area.

Demonstrators who did not follow the dispersal order were arrested.

It was not immediately clear how many people were taken into custody.