Nairobi - Human rights activists on Friday accused Kenyan police of executing three women who allegedly attacked a police station this month after pledging allegiance to the Islamic State group.In one video posted on social media by a human rights activist, two of the women can be seen sprawled on the ground with severe burns on their bodies. A man with a rifle opens fire at them. Another video posted online shows a woman burnt and lying on her back while being questioned about the attack.Police said they killed the three women on September 11 after they attacked the police station in Mombasa with a petrol bomb and knife. Police said the women had pledged allegiance to ISIS.Activist al-Amin Kimathi demanded that the police officers responsible for the executions be prosecuted."They should have been arrested for the information they can provide," Kimathi said. "They are more valuable alive than dead."Khelef Khalifa, the chairperson of the Muslims for Human Rights group, said the police explanation does not add up."Why kill disarmed young girls instead of apprehending them, taking them to the court of law?" Khalifa said.If anyone thinks that police executed the three women, they can take legal action and due process will be followed, said Charles Owino, a police spokesman. He said police considered the women to be terrorists and that the action taken was justified under the circumstances.Police on Friday charged Hania Said Sagar, widow of Islamic cleric Aboud Rogo, who authorities say was a key recruiter for Somali extremist group al-Shabab, with failure to disclose information about the attack's alleged mastermind.Kenya's police have long been accused of carrying out extra-judicial executions. Rights group Independent Medico Legal Unit says 520 extra-judicial killings have occurred since 2013.