Police refuse to comment whether a spate of attacks against western workers in Saudi Arabia are linked to militants in the Islamic State of Iraq and Syria (ISIS).
Four attacks are under investigation in the past month.
A Danish expat was shot in Riyadh when leaving his office.
A few days earlier, a Canadian expat was stabbed in the oil city of Dhahran.
Less than a month ago an American was killed and another hurt when a Saudi co-worker shot them after a row at work.
The three expats are all recovering from their injuries.
Saudi police declined to comment when asked if the crimes were linked or if any terror group had taken responsibility.
However, a poor video alleging to be mobile phone footage of the attack against the Danish expat has appeared online with ISIS claiming one of their militants was responsible for the shooting.
Saudi police say the video cannot be verified as either a film of the shooting or as coming from ISIS.
Only a few weeks ago, expats teaching English in Middle East schools were warned to take care and increase their personal security after a militant claiming to represent ISIS issued threats online.
ISIS has also called on supporters in Saudi Arabia to attack Shia Muslims, government workers and westerners.
The video was released by al-Battar Media Foundation and purports to record “Supporters of the Islamic State in the Land of the Two Holy Mosques”, a name some Islamists call Saudi Arabia.
The film includes short clips of speeches by ISIS leaders urging Saudis “to kill and spit upon” westerners.
The video seems to be taken from inside a car driving around Riyadh and shows a gunman opening fire with a pistol at a car.
Rumours about who may be behind the current wave of attacks are rife following the threat.
The attacks are a worrying escalation for expats in Saudi Arabia, which is not a country noted for violent crime.
The last reported murder of expats was seven years ago, when three French visitors were shot dead when camping in the north of the country.
Before that, hundreds died in clashes between rival Muslims and security forces in a bloody three year terror campaign that was eventually put down by the government.
The Saudi government has announced 70 individuals linked to ISIS are being held by security forces.