An American teacher and mother of twins was stabbed to death in the toilets of an Abu Dhabi shopping mall by a suspect in a black Muslim veil, police said Wednesday.
It was unclear what the motive was for Monday's attack in the upmarket Boutik Mall on Al Reem Island, which is popular with expats in the capital of the United Arab Emirates.
The stabbing comes little more than a month after US embassies in the Gulf, including the UAE, called for vigilance when a post on a jihadist website encouraged attacks on American and other international schools there, specifically on teachers.
The 37-year-old woman, who worked at an Abu Dhabi kindergarten, was stabbed by a person wearing a black robe, black gloves and a niqab -- a Muslim veil that conceals the face except for the eyes.
Her 11-year-old children were taken into police care until their father arrived from abroad.
The US embassy in Abu Dhabi confirmed the death of an American citizen, saying it was working with "all appropriate authorities to seek further information".
Police released security camera footage showing the suspect walking in and out of the mall, and shots of the knife used in the attack in a washroom following what they described as an "altercation".
"The victim was stabbed with a sharp object following an argument in the ladies toilets," the head of Abu Dhabi's police criminal investigations department, Colonel Rashid Bourscheid, was quoted by The National daily as saying.
- 'Reem Island Ghost' -
Police were still trying to determine the motive of the attack, as well as the identity and gender of the suspect, who the interior ministry said had been dubbed the "Reem Island Ghost".
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In the CCTV footage, the assailant is seen entering the mall shortly after 1:00 pm and then hastily leaving the restroom about 90 minutes later, as panicked shoppers scrambled.
The footage was accompanied by pictures of a bloodied kitchen knife and trails of blood splattered on the floor of the restroom.
The National quoted an employee at a nearby restaurant who heard two women arguing in the toilet and one threatening: "Sit down or I'll kill you".
The American died after being taken to hospital. She was not named but the Gulf News daily identified her by the initials "A.B.R".
The United Arab Emirates, of which Abu Dhabi is the largest, hosts millions of foreign workers and has built an image of a relatively liberal society among Gulf Arab nations.
In September it joined a US-led coalition against the Islamic State jihadist group in Iraq and Syria.
The stabbing took place on the same day as a recording attributed to IS spokesman Abu Mohammed al-Adnani urged Muslims to attack Westerners by any means, even if only to "spit on their faces".
Violent crime is relatively rare in Abu Dhabi although there have been attacks on foreigners elsewhere in the region.
In Saudi Arabia on Saturday, an assailant stabbed and wounded a Canadian while he shopped at a mall in Dhahran on the Gulf coast.
Last month, a Dane was shot and wounded in Riyadh -- an attack IS claimed Monday was carried out by its supporters.