The three sexual assaults on victims all took place in the Spring Boroughs and Semilong areas of Northampton on Sunday, December 1, Northamptonshire Police today said.
The first victim was approached in the early hours in Spring Lane, the second at around 2am, also in Spring Lane, and the third at around 11.50pm in Grafton Street.
Officers are appealing for information around any sightings of two to three men in a dark-coloured 4x4 vehicle in these areas at the relevant times.
A spokeswoman for Northamptonshire Police today said: "The men are all described as white, of average build, with Eastern European or Russian accents."
A 23-year-old Northampton man arrested in connection with the incidents remains in police custody today, Wednesday, December 4.
Increased police patrols are taking place in the Spring Boroughs and Semilong areas while investigations into the offences continue.
Anyone with information is asked to call Northamptonshire Police on 101, or Crimestoppers anonymously on 0800 555111.