LOS ANGELES (AP) — Tensions in Los Angeles escalated Sunday as thousands of protesters took to the streets in response to President Donald Trump’s extraordinary deployment of the National Guard, blocking off a major freeway and setting self-driving cars on fire as law enforcement used tear gas, rubber bullets and flash bangs to control the crowd.

Many protesters dispersed as evening fell and police declared an unlawful assembly, a precursor to officers moving in and making arrests of people who don’t leave. Some of those remaining threw objects at police from behind a makeshift barrier that spanned the width of a street and others hurled chunks of concrete, rocks, electric scooters and fireworks at California Highway Patrol officers and their vehicles parked on the closed southbound 101 Freeway. Officers ran under an overpass to take cover.

Sunday’s protests in Los Angeles, a sprawling city of 4 million people, were centered in several blocks of downtown. It was the third and most intense day of demonstrations against Trump’s immigration crackdown in the region, as the arrival of around 300 Guard troops spurred anger and fear among many residents.

The Guard was deployed specifically to protect federal buildings, including the downtown detention center where protesters concentrated.

Los Angeles Police Chief Jim McDonnell said officers were “overwhelmed” by the remaining protesters. He said they included regular agitators who show up at demonstrations to cause trouble.

Several dozen people were arrested throughout the weekend of protest. One was detained Sunday for throwing a Molotov cocktail at police, and another for ramming a motorcycle into a line of officers.

Trump responded to McDonnell on Truth Social, telling him to arrest protesters in face masks.

“Looking really bad in L.A. BRING IN THE TROOPS!!!” he wrote.

Clashes escalate as National Guard troops arrive

In Los Angeles on Sunday morning, National Guard troops stood shoulder to shoulder, carrying long guns and riot shields as protesters shouted “shame” and “go home.” After some closely approached the guard members, another set of uniformed officers advanced on the group, shooting smoke-filled canisters into the street.

Minutes later, the Los Angeles Police Department fired rounds of crowd-control munitions to disperse the protesters, who they said were assembled unlawfully. Much of the group then moved to block traffic on the 101 freeway until state patrol officers cleared them from the roadway by late afternoon.

Nearby, at least four self-driving Waymo cars were set on fire, sending large plumes of black smoke into the sky and exploding intermittently as the electric vehicles burned. By evening, police had issued an unlawful assembly order shutting down several blocks of downtown Los Angeles.

Flash bangs echoed out every few seconds into the evening.