PORTLAND, Ore. - Protesters in Portland, Oregon, defied police orders to disperse and threw rocks, frozen or hard-boiled eggs and commercial-grade fireworks at officers as unrest in the Northwest city continued early Saturday.

An Oregon State Police Trooper was struck in the head by a large rock and suffered a head injury, police said in a release. The trooper’s condition was not immediately known.

Some demonstrators filled pool noodles with nails and placed them in the road, causing extensive damage to a patrol vehicle, police said. Oregon State Police worked with Portland officers to clear the protesters.

“Officers are having rocks and chunks of concrete thrown at them,” police said on Twitter. “Individuals in the crowd are shining lasers trying to blind officers.”

Since George Floyd was killed in Minneapolis, protests over racial injustice and police brutality have occurred nightly for 70 days.

Portland police declared an unlawful assembly Friday night at the Penumbra Kelly public safety building, ordering everyone in the area to leave. Authorities had previously warned people not to trespass on the property.

Protesters remained for several hours before officers began to rush the crowd away from the building using crowd-control munitions early Saturday. Several people were arrested, police said.

“As arrests were made, certain crowd members began throwing rocks towards officers,” police said in a statement. “As this criminal activity occurred, the crowd also blocked all lanes of traffic on East Burnside Street, not allowing vehicles to pass by. Several people in this group wore helmets and gas masks as well as carried shields.”

Police said Saturday that they arrested 24 people during the overnight demonstration. Most of those arrested were from Portland, while one man was from Oakland, California, and another was Tulsa, Oklahoma. Most were in their 20s or 30s.

The charges included assault on an officer, interfering with an officer, disorderly conduct and resisting arrest.

Most of the crowd left the area by about 2:30 a.m. Saturday, police said.

Democratic Mayor Ted Wheeler said this week the violent protesters are also serving as political “props” for President Donald Trump in a divisive election season where the president is hammering on a law-and-order message. Trump has tried to portray the protesters as “sick and dangerous anarchists” running wild in the city’s streets.

The chaos that started Thursday night lasted into Friday morning in a residential neighborhood about 6 miles (10 kilometers) from downtown. The demonstrations this week had been noticeably smaller than the crowds of thousands who turned out nightly for about two weeks in July to protest the presence of U.S. agents sent by the Trump administration to protect a federal courthouse that had become a target of nightly violence.

This week’s clashes have, however, amped up tensions after an agreement last week between state and federal officials seemed to offer a brief reprieve.

The deal brokered by Democratic Gov. Kate Brown called for agents from the U.S. Customs and Border Protection, U.S. Marshals Service and U.S. Immigration and Customs Enforcement to pull back from their defense of the Mark O. Hatfield Federal Courthouse starting July 30.

Early Friday, as peaceful demonstrations proceeded elsewhere in the city, a group of people gathered at a park in eastern Portland and marched to the local police precinct, where authorities say they spray-painted the building, popped the tires of police cars, splashed paint on the walls, vandalized security cameras and set a fire in a barrel outside the building. One officer was severely injured by a rock, police said, but no additional details were provided.

Tear gas was used by police on protesters Wednesday for the first time since the U.S. agents pulled back their presence in the city. But officers did not use it Thursday despite declaring the demonstration an unlawful assembly.

Portland police have arrested more than 400 people at protests since late May. U.S. agents arrested at least an additional 94 people during protests at the federal courthouse in July.