A number of emergency services were called to Warrior Square, in St Leonards, after a woman was hit by a bus, the ambulance service confirmed.
Traffic reports said the A2102 Warrior Square one-way street near the A259 Grand Parade was partially blocked due to a collision.
The South East Coast Ambulance (SECAmb) said it sent paramedics to the scene at 2.45pm.
A spokesman for the ambulance service said reports suggested a female patient was hit by a bus.
The air ambulance was called to the scene and assisted the patient, according to the spokesman.
The woman was taken to Royal Sussex County Hospital, in Brighton, via road ambulance with injuries described as ‘potentially serious’.
No other vehicle is reported to have been involved and the road and air ambulances have left the scene.
Congestion was reportedly affecting Grand Parade.
Stagecoach SouthEast took to Twitter to say the 26 service from Conquest Hospital was cancelled while the 22 service from Harley Shute would be delayed by approximately 20 minutes.
The company said the disruption was caused by ‘an incident at Warrior Square’.
Sussex Police has been approached for comment.