Police in the United Arab Emirates have arrested a local woman on suspicion of stabbing to death an American teacher in a toilet at an Abu Dhabi shopping mall.

Colonel Rashid Borshid of the Abu Dhabi police told a news conference yesterday that the suspect also placed a makeshift bomb outside the front door of an apartment of an American doctor living in the UAE less than two hours after Monday’s killing.

The bomb was dismantled and no one was hurt.

The victim of Monday’s killing was identified by ABC News and other US media organisations as kindergarten teacher Ibolya Ryan, the Romanian-born mother of 11-year-old twins.

ABC said the woman had previously taught at a school in Colorado.

Anonymous post on jihadist web forum had called for attacks on American teachers in the region

The suspect had been filmed on security cameras at the mall wearing a traditional black Arab robe and gloves.

“The face-covered suspect is now in police custody,” Interior Minister Sheikh Saif bin Zayed al-Nahayan said yesterday.

Asked if police saw the sequence of events as a terrorist attack, Borshid said: “This is under investigation now, and I cannot say yes or no now.” The US Embassy in the UAE – a wealthy Gulf Arab state and US ally – posted a statement in October saying an anonymous post on a jihadist web forum had called for attacks on American teachers in the region, although it said it had no credible evidence of any such plots.

Supporters of the Islamic State group in Iraq and Syria have urged Muslims to attack Western expatriates in retaliation for US-led air strikes on its fighters.

The UAE has participated in the campaign and is a strong opponent of a variety of Islamist groups.

A spate of attacks on Westerners in neighbouring Saudi Arabia has raised concern there that the assaults may represent the start of a “lone wolf” campaign by jihadi militants.