Detectives are continuing to search for those responsible for yesterday's bomb blast in Derry.
A device was left in a busy shopping area on Shipquay St at around lunchtime.
Nobody was injured as police had evacuated the area.
They acted after three masked men entered a business premises an hour before the explosion, and warned staff that a bomb had been planted.
Political leaders have condemned the attack, believed to have been carried out by dissident republicans