WASHINGTON >> Police used pepper spray on some of the thousands of pro-Palestinian protesters who gathered outside the U.S. Capitol on Wednesday while Israeli Prime Minister Benjamin Netanyahu spoke to Congress.

Shortly before Netanyahu began speaking, U.S. Capitol Police said some protesters had become violent.

“The crowd failed to obey our order to move back from our police line. We are deploying pepper spray towards anyone trying to break the law and cross that line,” police said in a statement.

Protests were peaceful for the first few hours until about half an hour before the speech when demonstrators began a march and faced a blockade from police who used pepper spray, injuring some protesters.

Authorities had closed off traffic around the Capitol before the speech in unusually tight security.

Netanyahu referred to the protesters outside and said he had a message for them. “When the tyrants of Tehran who hang gays from cranes and murder women for not covering their hair are praising, promoting, and funding you, you have officially become Iran’s useful idiots,” he said, using a Cold War-era term for people who are manipulated for a political agenda.

A stage decked with banners included one declaring the Israeli leader a “Wanted War Criminal” in reference to an arrest warrant sought by International Criminal Court prosecutors. Netanyahu vehemently denies war crimes allegations.

Nearby, demonstrators placed nearly 30 human-size cardboard coffins wrapped in Palestinian flags. Traffic was barred from several roads near the Capitol.

“I want all aid (to) be suspended to Israel due to its actions in Gaza,” said Bradley Cullinan, who said he traveled to the area from Columbus, Ohio, 400 miles (640 km) away.

Oscar-winning actor Susan Sarandon took to the stage and condemned the death toll. “No one is free until everyone is free,” Sarandon said.

Dozens of Democratic lawmakers skipped Netanyahu’s speech to Congress, expressing dismay over the thousands of civilian deaths and the humanitarian crisis from Israel’s campaign in Gaza.

Members of an ultra-Orthodox Jewish group carried Palestinian flags and signs reading “Free Palestine” and “Anti-Zionism is not antisemitism,” while a group of younger protesters danced to Arabic music and carried large banners reading “Stop Arming Israel” and “Stop War Crimes in Gaza.”

Pro-Palestinian groups and university students have for months protested in the U.S. against Israel’s offensive in Gaza, a Hamas-ruled enclave where health authorities say nearly 40,000 Palestinians have been killed and nearly all of its 2.3 million people have been displaced.

Israel’s military assault followed an Oct. 7 attack by Hamas, whose militants surged into Israel, killing 1,200 people and taking around 250 hostages, according to Israeli figures.

ICC prosecutors say there are reasonable grounds to believe Netanyahu and Israeli Defense Minister Yoav Gallant as well as Hamas leaders Yahya Sinwar, Mohammed Al-Masri and Ismail Haniyeh, bear criminal responsibility for alleged war crimes and crimes against humanity.