Two men and two women have been arrested after a Merseyside police officer was hit and killed by a stolen pick-up truck involved in a high-speed chase.
PC Dave Phillips, 34, died after being struck by the stolen vehicle on Wallasey Dock North Road in the early hours of Monday morning following a burglary at an estate agency.
Merseyside police said in a statement on Tuesday afternoon that two men, aged 18 and 30 and from Oxton and Wallasey in Wirral, had been arrested on suspicion of murder.
On Wednesday the police force said two women, aged 19 and 34 and from Wallasey, had been arrested on suspicion of assisting an offender.
All four are still in custody, a police spokeswoman told BuzzFeed News.
Yesterday, police thanked the public for their support following an appeal for information over the death of Phillips.
Detective Chief Superintendent Paul Richardson said:
Since the investigation was launched yesterday we have been inundated with calls from members of the public and as a result we are following up a number of positive lines of inquiry.
From the hundreds of supporting and caring comments on social media and media websites yesterday it is obvious that there is overwhelming support for the police and that the public appreciate the work undertaken by officers like PC Phillips to keep their communities safe.
He also urged anyone with any potential information to come forward and contact police.
Phillips died after being struck by the Mitsubishi pick-up when it mounted a central reservation.
He had just deployed a "stop stick" to try to puncture the vehicle's tyres and bring it to a stop.