A man and a woman have been left with burns after a suspected acid attack involving two men on a moped.
Northamptonshire Police said the pair had a “noxious substance” squirted at them as they stood at a zebra crossing in Daventry.
Police said the man, 23, was left with minor burns to his forehead, and the 19-year-old woman with minor burns to her legs.
Police described it as “an extremely harrowing incident”.
The victims, who were on their way home from a night out before the attack in Park Leys, were treated at the scene by paramedics at about 01:30 BST before being taken to hospital.
The rider of the moped is described as wearing grey joggers, trainers, a cream-coloured hoodie and a white helmet.
His passenger was white and had dark hair, and was wearing dark clothing. One of them pulled out a machete before they drove off.
“We would urge people to be extremely vigilant to this type of incident which, as evidence suggests, is becoming increasingly common in this country,” said Det Ch Insp Louise Hemingway.
“We are appealing for anyone who has information to contact us.”