Iranian protests that began Dec. 28 saw security forces shift to live ammunition by January 8, with over 3,000 deaths estimated nationwide.

The death toll over 16 days of mass anti-government protests in Iran reached 2,000 as of Monday, according to data published by the the U.S.-based HRANA.

Amid a near-total communications blackout, witness footage trickling out of Iran paints a picture of how the country’s largest uprising in decades spread — and turned deadly.

A source inside Iran who was able to call out told CBS News on Tuesday that activist groups working to compile a full death toll from the protests, based on reports from medical officials across the country, believed the toll was at least 12,000, and possibly as high as 20,000.

Erfan Soltani, a 26-year-old Iranian man, has been sentenced to death in Iran amid widespread protests and a deadly government crackdown, according to human rights groups.

Trump has repeatedly threatened military action over Tehran's severe crackdown on the protests. Around 2,000 people have been killed in the protests, an Iranian official told Reuters, blaming people he called terrorists for the deaths of civilians and security personnel. Human rights groups had previously tallied around 600 deaths.

The Trump administration allegedly made the first high-level contact with the Iranian opposition amid intensifying nationwide anti-regime protests.