Three policemen were treated for shock after republican dissidents attempted to bomb a two-car RUC patrol in Derry early today.
A device exploded at the side of the road as officers were on their way to examine a burning vehicle in the city's Shantallow area.
Security chiefs said it was a deliberate attempt to lure the RUC men into a trap.
The second unmarked armoured car caught the force of the explosion, but the officers inside escaped unhurt.
A car had been set on fire close to a number of houses under construction in an area known at the Cornshell Fields.
A number of telephone calls were then made, and the bomb detonated as the passing patrol responded.
Republicans opposed to the Northern Ireland peace agreement have been blamed.
The attack was the latest in a series on police and troops by dissidents in the greater Derry area this year.
PA