A woman has fallen from the flyover on Queens Drive, leading police to block the road off during rush hour.
Emergency services were called to the roundabout between County Road and Rice Lane shortly before 3pm to reports that a woman had been found injured.
Police officers put a number of road closures in place close to the Alsop Fitness Centre as paramedics rushed to help the woman.
The victim, believed to be in her 20s, was then rushed to hospital a short time later for treatment.
Her condition is not yet known.
Merseyside Police have advised motorists to stay away from the area while emergency services deal with the incident.
In a statement, a spokesperson for the force said: "We can confirm that emergency services are in Walton after a woman was found injured this afternoon, Wednesday 28 October.
"At 2.50pm, officers and the ambulance service were called to the Rice Lane flyover to reports of a woman in her 20s having fallen.
"She has been taken to hospital for assessment of her injuries.
"A road closure will be in place as we deal with the incident.
Keep up to date with the latest news in your area by entering your postcode below
"Please take an alternative route and thanks for your patience."
According to traffic site INRIX, queues are beginning to build around the area and the road is likely to remain closed for some time.
The site said: "A59 Rice Lane closed, queueing traffic due to police incident at A5058 Queens Drive. On the roundabout.
"The road underneath the A5058 is closed."
