According to the NetBlocks traffic monitoring group, Internet traffic in Iran fell to nearly zero on Thursday night, shortly before a round of mass demonstrations was scheduled to begin. NetBlocks saw the blackout as "an attempt to suppress sweeping protests while covering up reports of regime brutality."

The nationwide blackout was presaged by dramatic losses of connectivity in the capital of Tehran and other cities, a detail confirmed by Ali Safavi of the National Council of Resistance of Iran (NCRI).

"Around 1 p.m. local time, the Internet traffic dropped," Safavi told Fox News Digital. "The internet was cut off in Lordegan, Chaharmahal, and Bakhtiari provinces as battles erupted."

The NCRI said at least seven people were killed in those cities on Wednesday by "direct fire from the criminal Revolutionary Guards and the suppressive forces loyal to the regime's Supreme Leader Ali Khamenei."

"This brings the number of confirmed martyrs killed on the path to freedom to 44," the NCRI said.

"Millions of Iranians from north to south and east to west have been out in the streets until nighttime. Over the past 12 days, more young people have laid down their lives to free Iran," Safavi said.

CBS News and the Associated Press (AP) quoted sources in Tehran who confirmed Internet access was shut down across the city on Thursday, even as crowds of "unprecedented" size massed on the streets. The source in question became unreachable shortly after delivering this report, leading CBS to conclude the communications blackout had been extended even further.

The AP added that international telephone networks also appear to have been cut off on Thursday, including both landlines and mobile phone services. "Such outages have in the past been followed by intense government crackdowns," the AP observed.

The trigger for the intensified crackdown and communications blackout appears to have been a call for mass demonstrations by Crown Prince Reza Pahlavi, son of the late shah who was deposed and driven into exile by the 1979 Islamic revolution. Some of the protest chants include praise for the shah and calls for the monarchy to return, sentiments that are technically punishable by death under the Ayatollah's regime.

"Millions of Iranians demanded their freedom tonight. In response, the regime in Iran has cut all lines of communication. It has shut down the Internet. It has cut landlines. It may even attempt to jam satellite signals," Pahlavi said on Thursday.

"I want to thank the leader of the free world, President Trump, for reiterating his promise to hold the regime to account. It is time for others, including European leaders, to follow his lead, break their silence, and act more decisively in support of the people of Iran," he said.