The death toll from nationwide protests in Iran spiked Tuesday to at least 2,000 people killed, activists said, as Iranians made phone calls abroad for the first time in days after authorities severed communications during a crackdown.

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.

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

Iran has deployed new techniques to swiftly and decisively crush nationwide protests, signaling a tactical shift by a regime that now views domestic dissent as an extension of the summer war with Israel.

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.

Demonstrations in Iran began in December when the value of the Iranian rial plunged against the US dollar and people took to the streets in Tehran