At least 4,519 people have been killed in Iran since protests erupted at the end of December, according to new figures released on Wednesday by the U.S.-based Human Rights Activists News Agency (HRANA).

The group said it has verified 4,519 deaths so far, with more than 9,000 additional cases still under investigation. Those killed include 4,251 demonstrators and 197 members of the security forces.

Iran’s internet shutdown remains largely in place, limiting the flow of information. However, images that have begun to emerge are revealing the scale of the violent crackdown on mass protests that took place on January 8 and 9.

HRANA said the true toll could be significantly higher as verification continues and access to affected areas remains restricted.