KABUL, Afghanistan (Reuters) - Enraged Afghans took to social media on Wednesday to demand severe punishment for the kidnapping and killing of a six-year-old girl in the capital Kabul.

Kidnapping has become more frequent in conflict-ridden Afghanistan in recent years, with Afghans of all income levels, as well as foreigners, potential targets.

The interior ministry said the girl, named Mahsa, was abducted on Sunday with her captors demanding a ransom of $300,000.

Kabul police then arrested two men in a raid and released a video clip showing the pair, in their 20s, apparently confessing to the crime. They said in the video that they had picked up the child on a motorcycle, took her to a rented room and, when the ransom failed to arrive, they killed her.

Afghans voiced outrage over the girl’s killing in hundreds of social media posts.

A spokesman for President Ashraf Ghani said the killing deeply saddened him and London-based human rights organization Amnesty International condemned it.

“We are horrified to hear the news of a 6-year-old girl’s murder in Kabul. Afghanistan’s children must be protected at all costs,” Amnesty said on Twitter.

“Such cases are intolerable and have no place in our culture,” Jamshed Rasooli, spokesman for the attorney general, said in a statement, adding police had been asked to expedite their investigation so the case could be prosecuted.

This month, the U.S. Embassy posted a security alert warning that U.S. citizens were priority kidnapping targets of both militant groups and criminal gangs.