A motorbike passenger was rushed to hospital with serious injuries while the rider "left the scene" after a crash with a car.
The red and white bike hit a grey Mercedes car on Childwall Valley Road, Netherley, by the junction with Garden Lodge Grove at around 1.52pm today.
The driver of the car stayed at the scene and is assisting police with their enquiries.
A section of Childwall Valley Road remains cordoned off between the junctions with Kings Drive and Garden Lodge Grove and traffic has been diverted.
The damaged motorbike and car remain on scene while officers continue their investigations.
A statement from Merseyside Police said: "We were called at 1.55pm today following reports of a road traffic collision involving a car and a motorbike on Childwall Valley Road, Netherley.
"The rider of the bike left the scene prior to patrols arriving. The male pillion passenger has been taken to hospital with serious injuries.
"The driver of the car, a Mercedes, stopped at the scene and is assisting with enquiries.
"An investigation is underway. Childwall Valley Road is currently closed between Kings Drive and Garden Lodge Grove while enquiries are being carried out.
"Anyone who witnessed the collision is asked to DM @MerPolCC, or call 101 quoting log 509 of 18 June."
Two ambulances from North West Ambulance Service attended the scene but only one was required to transport the patient to hospital.
Merseyside Police tweeted a warning to motorists to avoid the area due to Childwall Valley Road being closed between Kings Drive and Garden Lodge Grove.
The force said: "Traffic is being affected so please avoid the area if possible & allow extra time for your journey. Please drive safely."
