The US embassy in the United Arab Emirates has urged its citizens to be vigilant, after a burqa-clad woman allegedly stabbed an American teacher to death in the public toilets of a shopping mall.
Dalal al-Hashemi, 38, a UAE citizen of Yemeni origin was arrested after the fatal stabbing of Ibolya Ryan, 37, and according to police sources was acting as part of a terror cell.
She is charged with murdering the teacher, and then planting a bomb outside the house of an American-Egyptian doctor.
The US embassy in the UAE has warned its 100,000 citizens in the country to be wary of further terror attacks, and to take precautions to ensure their safety.
"We suggest that all US citizens be vigilant of their surroundings and events unfolding around them," the statement said, adding "Vary your routines and schedules."
Speaking to ABC News, local police said that the woman was not operating as a "lone wolf" attacker, but as part of a group.
Sources told the network that others had been arrested after a raid on al-Hashemi's home, which was being used as a "base of operations".
Ryan was stabbed to death in the public toilets of the Boutik Mall with a butcher's knife after the attacker allegedly posed as a disabled person in need of assistance. The bomb, containing nails and a gas cylinder, did not detonate.
Police said that Ryan and the doctor were targeted because of their nationality.
Some have speculated that the attack was motivated by a call from jihadist group Islamic State (Isis) for supporters to launch terror attacks on home soil.
Air strikes have been launched against Islamic State targets in Iraq by a US led coalition of countries including UAE.
"There is a lot of sympathy for Isil [Islamic State] in the region after the US bombing campaign on their positions in Iraq and Syria," Hassan Hassan, an analyst at the Delma Institute, a research centre in Abu Dhabi told the Telegraph. "It could be that this is a response to the call by Isil to take revenge on countries taking part in the air strikes."
Foreign residents spoke of the fear the attack had provoked in the country's sizeable ex-pat community.
"This could have been any one of us," a British woman told the Guardian.
"In the UAE there are no crimes like this, so we all let our guard down," she said. "Now we have to put it back up again."