Anti-government chants filled the streets of Iran’s capital on late Saturday, as protesters pressed the largest challenge to the Islamic Republic in more than three years despite a deadly crackdown under the cover of an internet blackout.

Iran has blamed the United States for the demonstrations, which ignited in Tehran two weeks ago over economic hardship and have since spread nationwide with calls to oust the clerical leadership.

Rights groups reported dozens of deaths and warned Saturday that authorities were intensifying their crackdown.

Little information has filtered out after an internet shutdown, with monitoring group NetBlocks showing virtually no connectivity since Thursday.

U.S. President Donald Trump said his country was “ready to help” the movement, after warning Iran was in “big trouble” over efforts to suppress the protests.

“Iran is looking at FREEDOM, perhaps like never before. The USA stands ready to help!!!” Trump posted Saturday on Truth Social.

According to The New York Times, Trump was recently briefed on options for possible military strikes.

U.S. officials, speaking anonymously to the newspaper, said Trump has not yet made a final decision on another intervention, after Washington joined Israel’s 12-day war against Iran in June.

Crowds gathered again on Saturday in northern Tehran, setting off fireworks and banging pots as they shouted slogans in support of the ousted monarchy, according to video verified by AFP.

Other videos, which AFP could not immediately verify, showed demonstrations in additional parts of the capital, with protesters chanting anti-government slogans.

Reza Pahlavi, the U.S.-based son of Iran’s deposed shah, urged Iranians to stage more targeted protests over the weekend.

“Our goal is no longer just to take to the streets. The goal is to prepare to seize and hold city centers,” Pahlavi said in a video posted on social media.

The demonstrations have posed one of the biggest challenges to Iran’s theocratic rulers since the 1979 Islamic Revolution.

After initially calling for restraint and acknowledging economic grievances, authorities have since hardened their stance.

Supreme Leader Ayatollah Ali Khamenei, in a defiant speech on Friday, lashed out at “vandals” he said were doing Trump’s bidding.

‘Not safe’

Amnesty International said it was analyzing “distressing reports that security forces have intensified their unlawful use of lethal force against protesters” since Thursday.

Norway-based Iran Human Rights said at least 51 people have been killed so far, warning the actual toll could be higher.

The group posted images it said showed bodies of people shot dead during protests lying on the floor of Alghadir Hospital in eastern Tehran.

“These images provide further evidence of the excessive and lethal use of force against protesters,” Iran Human Rights said.

On Friday in Tehran’s Saadatabad district, protesters chanted anti-government slogans including “death to Khamenei” as cars honked in support, video verified by AFP showed.

Other images circulated on social media and by Persian-language television channels outside Iran showed similarly large protests elsewhere in the capital, as well as in the eastern city of Mashhad, Tabriz in the north, and the holy city of Qom.

In the western city of Hamedan, a man was shown waving a Shah-era Iranian flag bearing the lion and sun.

The same flag briefly flew over Iran’s embassy in London after protesters reached the building’s balcony, witnesses told AFP.

On Thursday and Friday, an AFP journalist in Tehran saw streets deserted and plunged into darkness.

“The area is not safe,” said a cafe manager as he prepared to close around 4 p.m.

‘Price to pay’

Authorities say several members of the security forces have been killed.

State television aired images Saturday of funerals for security personnel killed in the unrest, including a large gathering in the southern city of Shiraz.

It also broadcast footage of buildings, including a mosque, on fire.

Iran’s army said in a statement it would “vigorously protect and safeguard national interests” against an “enemy seeking to disrupt order and peace.”

Global leaders urged restraint, with European Commission President Ursula von der Leyen saying Europe supported Iranians’ mass protests and condemned the “violent repression” of demonstrators.

On Saturday, the start of Iran’s workweek, one man in Tehran said he was unable to check his work email.

“This is the price to pay before the victory of the people,” he said.