An angry mob in the center of the Afghan capital, Kabul, has killed a woman and set her body alight for allegedly burning a copy of the Koran.

Police and witnesses say the killing took place near the Shah-e Doh Shamshira shrine on March 19.

"We were watching this incident. She burned the Koran,” one eyewitness told RFE/RL's Radio Free Afghanistan.

“A lot of people gathered around the spot,” he added. “They burned her."

The head of Kabul's criminal police, General Farid Afzali, told the AFP news agency that the woman's body was then thrown into the Kabul River.

Heather Barr, a senior researcher for women's rights in Asia for Human Rights Watch (HRW), identified the victim as 27-year-old Farkhunda.

A security official quoted the family of the victim as telling investigators that she had been suffering from mental illness for many years,

Footage obtained by RFE/RL shows a large crowd comprised mainly of young men repeatedly kicking and beating the woman. Some throw stones and buckets at her as she struggles to get off the ground.

The assault on the woman then continues as she lies on the ground, clearly unconscious and bleeding profusely.

Some men in the crowd can be heard shouting "Allahu Akbar" ("God is great").

Interior Ministry spokesman Sediq Sediqqi said a probe into the "very unfortunate" event was under way.

He also said that four suspects had been arrested in connection with the attack.

The Reuters news agency quoted HRW's Barr raising concerns as to whether enough had been done to stop the mob.

"I would certainly hope the government would be trying to arrest and prosecute everyone who was involved and doing an internal investigation into whether the police response was appropriate," Barr said.

In 2012, the revelation that copies of the Koran had been burnt at the U.S.-run Bagram prison near Kabul sparked five days of violent anti-U.S. riots and attacks across the country.

Thirty people were reported killed in the violence, including four Americans.

With reporting by AFP, AP, and Reuters