Iranian protesters on Thursday escalated their challenge to the country’s clerical leadership, with demonstrations spreading nationwide and turning into the largest unrest seen in nearly two weeks. Authorities responded by cutting internet access across the country as the reported death toll from the crackdown continued to rise.

The protest movement began on December 28 with a shutdown of Tehran’s historic bazaar after Iran’s rial plunged to record lows. What started as economic anger has since transformed into broader anti-establishment demonstrations, including large-scale rallies in the capital and major provincial cities.

The unrest has put pressure on Iran’s leadership under Supreme Leader Ayatollah Ali Khamenei, who is already grappling with a deepening economic crisis after years of sanctions and the aftermath of the June war against Israel.

Adding to the tension, US President Donald Trump warned on Thursday that Washington would take severe action if Iranian authorities “start killing people”, saying the US would “hit them very hard”.

Rights groups accuse Iranian security forces of using lethal force against protesters. Norway-based NGO Iran Human Rights (IHR) said on Thursday that at least 45 protesters, including eight minors, have been killed since the demonstrations began. According to the group, Wednesday was the deadliest day so far, with 13 confirmed deaths.

“The evidence shows that the scope of the crackdown is becoming more violent and more extensive every day,” IHR director Mahmood Amiry-Moghaddam said, adding that hundreds of people have been wounded and more than 2,000 arrested.

Iranian media and official statements, however, have acknowledged at least 21 deaths since the unrest began, including members of the security forces, according to an AFP tally. On Wednesday, an Iranian police officer was killed west of Tehran while trying “to control unrest”, the Fars news agency reported.

Despite the crackdown, protests continued into Thursday night. Social media images verified by AFP showed a large crowd gathering on Ayatollah Kashani Boulevard in northwest Tehran, while other footage showed demonstrations in the western oil city of Abadan.