Two men are being hunted following a suspected acid attack in Northamptonshire, police said.
A 23-year-old man and a 19-year-old woman received minor burns on Saturday August 26, after the men sprayed them with a noxious substance, believed to be acid.
The attack took place as the pair were using a zebra crossing in Park Leys, Daventry, shortly before 1.30am.
The offenders pulled up beside the victims to perform the attack while mounted on a moped. They produced a machete before driving off.
The man received burns to his forehead and the woman to her legs. Both victims were treated for their injuries at Northampton General Hospital.
The driver of the moped is was wearing grey joggers, trainers, a cream hoodie and a white helmet.
The passenger was white, with dark hair and was wearing dark clothing.
Det Chief Inspector Louise Hemingway, of Northamptonshire Police, said: "This was an extremely harrowing incident for the two victims who were making their way home after a night out.
"We would urge people to be extremely vigilant to this type of incident which, as evidence suggests, is becoming increasingly common in this country.
"We are appealing for anyone who has information to contact us. We are particularly keen to trace a moped which was seen in London Road at 12.45am as well as in other parts of the town centre around the time of this attack."
Anyone with information should call Northamptonshire Police on 101, quoting incident 53 of August 26, or Crimestoppers, in confidence, on 0800 555111.
The substance used in the attack is now being tested to determine what it was, police said.