Police have released CCTV footage of a car bomb exploding outside the courthouse on Bishop Street in Londonderry.
Two men were arrested on Sunday morning in connection with the attack.
In the footage a man can be seen fleeing from the car.
A group of young people walk directly past the vehicle shortly before it is ripped apart by the bomb.
Police have said that their main line of inquiry is that the dissident republican group, the New IRA, are behind the attack.
On Sunday PSNI Assistant Chief Constable Mark Hamilton described it as a ‘significant attempt to kill’.
No-one was injured in the attack.