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.

Iranian student Rubina Aminian was shot in the head at close range, joining thousands allegedly killed by government forces, according to Iran Human Rights, a Norway-based group.

Mobile phones in Iran were able to call abroad Tuesday after a crackdown on nationwide protests in which the internet and international calls were cut.

The protests in Iran could have a sweeping effect in a region already jolted by historic changes over the past year. Four CFR fellows assess how Israel, the Gulf States, Lebanon, and Turkey view the

Iran's government imposes five-day internet blackout as nationwide protests intensify, with at least 646 people killed and over 10,000 arrested during the crackdown.

At least 544 people have been killed in anti-government protests across Iran, according to data published on Sunday by the Human Rights Activists News Agency.

The difficulty of tracking the death toll from Iran's nationwide protests has been compounded by the government's decision to shut down the internet and international calling.

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.

The Iranian authorities have imposed an information blackout as they try to quell protests, but eyewitness testimony and videos conveying the deadly toll have made their way out.