Three PSNI officers and a pregnant woman were hurt when a police car crashed while responding to a road traffic collision report.
The police car and a Vauxhall Corsa, which was being driven by the pregnant woman, both smashed into a wall in Coleraine shortly before 5pm on Saturday.
All of the injured were rushed from the scene to hospital. None of the injuries is believed to be life-threatening.
It is understood that police had received reports of a road accident and the three officers were making their way to the scene when the collision occurred on the Wheatsheaf Road.
Part of the wall that the police car and the Vauxhall Corsa crashed into was demolished during the incident.
Eyewitnesses said it was lucky that nobody was killed.
Several ambulance and fire crews were called to the scene.
Photographs taken moments after the crash show how bricks from the wall had landed on the bonnet of the Vauxhall Corsa. Other images show the smashed windscreen of the PSNI car and a police officer being carried away from the scene on a stretcher by paramedics.
One witness, who arrived at the scene minutes after the smash, said: "There were fire crews and paramedics everywhere.
"It looked like a very nasty accident.
"People at the scene were saying that the police were responding to a call out when they crashed. Imagine if somebody had been walking beside that wall."
He added: "It doesn't bear thinking about what could have happened. "
Coleraine councillor David Barbour said it was lucky that nobody had been killed.
"It was a very bad accident judging from the scene and photographs. I was coming back from Limavady when I saw fire tenders and ambulances trying to get across heavy traffic. There was gridlock in the town. I contacted fire control and they told me it was an extensive accident."
The UUP man added: "It's very lucky that there were no fatalities or very serious injuries in this accident. That is an excellent road with a speed limit on it so I can't understand what happened."
The PSNI said that the Police Ombudsman has not been called to investigate. A PSNI spokesman added: "A road traffic collision involving a Vauxhall Corsa and a police vehicle occurred on the Wheatsheaf Road in Coleraine.
"The female driver of the Vauxhall and three police officers were taken to hospital for treatment for their injuries that are not believed to be life-threatening."