A second collision occurred on the Frank Perkins Parkway shortly after the first one left two people needing medical treatment.
Police were called at 8.09am to the first collision at Stanground involving three cars.
Police and the fire and ambulance services attended and the road was closed while recovery took place.
One driver was taken to Peterborough City Hospital with minor injuries and another later attended a walk-in centre, also with minor injuries.
The other driver was uninjured.
The second collision involved two cars in the tailback of the first crash. Both vehicles have since been cleared and there were no reported injuries.
It has been a bad morning on the roads with lengthy delays across the city, including on the A47 at Wansford following another crash, and on the Soke Parkway between the Thorpe Wood roundabout eastbound past Rhubarb Bridge.