A police officer was hit by three bullets in the attack at the Maxol filling station on Crumlin Road, Belfast, on Sunday evening, and is recovering in hospital.
Condemning the attack as an act of complete recklessness, chief constable George Hamilton said: "The Crumlin Road filling station was riddled with high-velocity gunfire at half past seven when people were going about their normal business, going to fill their car with fuel, buying lunches for children and all of that."
Detective superintendent Kevin Geddes said: "We have recovered bullets from a number of locations on the forecourt and in several cars. Any one of these could quite easily have killed or seriously injured local people, including the children who were at the station. Had any of the bullets hit the fuel containers we may have also been facing casualties from an explosion."
A spokesperson for Maxol said: "The shooting that took place at our Edenderry Service Station in Belfast on Sunday evening was both shocking and dreadful.
"Thankfully our licensees John and Sharon Bailey, our staff and remaining customers were unhurt. Our thoughts are with the injured officer and his family."
The officer who was shot was struck three times on the right arm, and underwent a three-hour operation. He will need further surgery.
A 36-year-old man arrested in connection with the incident remains in custody, is assisting police with their enquiries.
Detectives are keen to speak to anyone who noticed an Audi-type vehicle opposite the filling station at around 7.30pm on Sunday January 22, or anyone who has any other information that could help the investigation.
Anyone with information is asked to contact detectives on 101. Alternatively, information can be given to the Crimestoppers charity anonymously by telephoning 0800 555111.