Iranian demonstrators, angry that their government accidentally shot down a passenger plane, took to the streets for a third day on Monday. Videos from these protests appear to show security forces using live ammunition against demonstrators, something that Iran's government has denied.

All 176 people on the Ukraine-bound flight last Wednesday were killed. Iran initially said the Boeing 737-800 crashed because of a mechanical failure but and later said it downed the plane unintentionally. The majority of those who died were Iranians.

Demonstrations over the "unforgivable mistake" started over the weekend. Security forces have been "dispersing anti-regime protests quickly and harshly with tear gas and rubber bullets," NPR's Peter Kenyon reported.

They also reportedly used live ammunition against the protesters. Videos released by a human rights group and verified by The Associated Press show bloodied demonstrators being carried away from the scene. "Oh my God, she's bleeding nonstop!" one person in the video shouts, according to the wire service. Other videos show chaotic scenes of demonstrators fleeing security forces.

"Police treated people who had gathered with patience and tolerance," Tehran police Chief Hossein Rahimi told local media, according to the AP. "Police did not shoot in the gatherings since broad-mindedness and restraint has been the agenda of the police forces of the capital."

Tensions between the U.S. and Iran have ratcheted up dramatically since the U.S. killed a top Iranian military commander, Maj. Gen. Qassem Soleimani, in an airstrike in Baghdad earlier this month. President Trump has accused Soleimani of planning imminent attacks on U.S. citizens, without providing specific details or evidence.

After Soleimani's killing, vast crowds of mourners — many of them openly weeping — packed the streets in Tehran to pay their respects. Iranian leaders promised to avenge the killing and launched airstrikes against Iraqi bases housing U.S. troops. Those strikes caused no casualties.

Iran's military eventually said on Saturday that the plane was shot down near Tehran "as a hostile object due to human error at a time of heightened US threats of war," according to Iran's semiofficial Fars News Agency. The Iranians also placed a large amount of the blame on the U.S., saying its air defense units were particularly sensitive because of increased U.S. military flights in the area.

"Demonstrations that had been attacking the U.S. for killing Iran's top general quickly turned into calls of 'death to the dictator,' a reference to Supreme Leader Ayatollah Ali Khamenei," Kenyon reported.

The protests, which are largely driven by university students, emerged in many cities across the country, Kenyon notes.

In a tweet on Sunday, Trump called for Iran's leaders to exercise restraint. "DO NOT KILL YOUR PROTESTERS," the president wrote. "Thousands have already been killed or imprisoned by you, and the World is watching."

That same day, the U.K.'s ambassador to Iran, Rob Macaire, was briefly arrested near a demonstration in Tehran. Local media accuse him of "organizing and provoking people."

Macaire said he wasn't taking part in a protest. He said the event was advertised as a vigil for plane victims and that he was detained for half an hour after leaving the area. U.K. Foreign Secretary Dominic Raab decried the arrest as a "flagrant violation of international law."