Assistant Chief Constable Claire Rukas said: “A team of experienced detectives continues to work tirelessly to establish exactly what happened before, during and after this appalling incident.
“I am pleased that four arrests have now been made and hope this provides some reassurance to the public as those detained are questioned in connection with the discharge of the firearm.”
A large police cordon – which was put in place in Angel Row following the shooting – has now been lifted.
ACC Rukas thanked local businesses, residents and members of the public for their patience, support and understanding while the force carried out its investigation.
“The injured officer continues to recover in hospital and is receiving support from colleagues and loved ones,” she said.
“We ask that his privacy is respected at this time.
“Our thoughts remain with him, and with his family, friends and colleagues, who have all been affected by this deeply shocking incident.”