[Images of men police wish to speak with]
Officers from Barnet are renewing appeals to trace two men following a robbery.
On Wednesday, 2 March at about 15:50hrs, two men attended an address on Brent Street, NW4 to buy two laptops that had been advertised on Gumtree by the victim's sister.
As the men were looking at the laptops, one of them sprayed the victims - both women, aged 28 and 26 years - with a noxious substance.
A nine-year-old boy, who was also in the property, attempted to flee, but tripped and was also sprayed with the substance by the men as they ran from the property with both laptops.
Police and the London Ambulance Service attended and treated the three victims who were suffering from the effects of the noxious substance.
None of the victims required hospital treatment.
One of the victim's recorded footage of the suspects on her mobile phone.
Police are keen to hear from anyone who recognises either of the men seen in the footage.
They are both described as Eastern European. One of the men wore a dark coloured leather jacket and had short brown hair. The other man wore a black jacket and had a tattoo on his neck.
Anyone with any information is asked to contact police via 101 quoting reference numbers 205697 and 205700 or Crimestoppers anonymously on 0800 555 111.