A police officer suffered serious injuries in a "despicable attack" when he was knocked down by a van in Liverpool, police said.
A white Transit van was driven at the male officer in the Norris Green area of the city on Saturday evening after police attempted to stop the vehicle.
The driver has been arrested and taken to a police station in Merseyside.
The officer's injuries are not thought to be life-threatening after the incident at around 7.25pm, Merseyside Police said.
Detective Chief Inspector Martin Earl said: "This was a despicable attack on a police officer who was simply doing his job, trying to protect the communities of Merseyside.
"The officer has sustained serious injuries for which he is receiving treatment. He has also been left extremely shaken by his ordeal.
"His colleagues, both those who were with him at the time and others who attended following the incident, have been left shocked by this incident and are being provided with support."
On Saturday night, a road closure remained in place on Hasfield Road, where police were carrying out house-to-house inquiries.
Mr Earl added: "I would urge anyone with information about this incident, or who may have been passing Hasfield Road in their vehicle at the time and may have dashcam footage, to contact police. Any information could prove vital to our inquiries."