Police in Abu Dhabi are investigating the death of an American woman stabbed in a shopping centre toilets by a suspect wearing a Muslim veil, official media reported Wednesday.

The motive for Monday’s attack in Boutik Mall was unclear.

Witnesses said the 37-year-old American, who worked at a nursery school in Abu Dhabi, 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.

“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.

“Police are still trying to determine the reasons for the attack and the identity of the suspect, who fled the scene,” he said.

Emirati and US officials were not immediately available to comment.

The American died after being taken to hospital. She was not named but the police said she was divorced, and was the mother of 11-year-old twins who were taken into police care until their father arrived from abroad.

The assailant escaped after the attack.

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”.