Dissident republican group the Real IRA has said it carried out Monday night's car bomb attack in Londonderry.
The bomb was left close to the Ulster Bank and a row of shops in front of Da Vinci's hotel on the Culmore Road in the city.
It exploded shortly after midnight - about an hour after the warning was given. Dozens of homes were evacuated in the alert. No-one was injured.
However, the bank and several shops were damaged.
The area had been cleared when the bomb exploded. However, a police officer, who was standing close to the cordon, was blown off his feet by the blast.
Masonry and glass from smashed windows were strewn across the Culmore Road.
Throughout the night, army bomb experts examined the wreckage of the Vauxhall Corsa car that contained the bomb.
The bank is badly damaged.
The Real IRA contacted the office of a newspaper on Tuesday morning to say it was responsible for the attack.
It is not the first time it has targeted the Culmore Road branch of the Ulster Bank.
Last year, it said it was responsible for sending bullets to relatives of police officers working in the branch.
There have been a number of attacks in recent months which have been blamed on dissident republicans.
In August, a car containing 200lb of explosives went off outside Strand Road police station in the city, causing substantial damage.
Two men hijacked a taxi in the Bogside, loaded the bomb into the driver's car and ordered him at gunpoint to leave it at the station.
The area around the explosion remains cordoned off.
There has been severe traffic disruption to traffic in Derry City Centre, Pennyburn Roundabout and the Waterside on Tuesday morning as a result of the bomb.
The following roads are closed: Culmore Road from Culmore Roundabout to Pennyburn Roundabout; Strand Road between Pennyburn Roundabout and Duncreggan Road and Buncrana Road between Pennyburn Roundabout and Pennyburn Pass.
They are likely to remain closed until the early evening.
Northern Ireland Secretary of State Owen Paterson said the government would "not allow these people to achieve their aim".
He said the authorities would tackle those responsible and would "smoke them out" and "bear down on them".
The Northern Ireland Deputy First Minister Martin McGuinness said he condemned "the futile activities of these conflict junkies".
Speaking from Birmingham, where he is attending the Conservative Party Conference, he said: "The objectives of these people are to destroy the peace process; to break the unity of the Executive; to turn back the clock on policing and to embarrass Sinn Fein.
"On all four counts they have been failing miserably."
DUP MP Gregory Campbell said the bomb would cause "massive inconvenience" to schools, work and tourists.
"There is unanimous support across the political divide for condemnation of this," he said.
"We need information from local people, translated into evidence before a court and a conviction.
"Let's get beyond condemnation and get these people behind bars."
Mayor of Derry Colum Eastwood was at the scene when the device exploded.
"I saw the bomb go off. We were not far away," he said.
"It is just shocking that someone would put a bomb anywhere, but especially at a commercial centre.
"I do not know what these people are hoping to achieve. They say they love their country but they spend their time trying to destroy it. The people of this city will be very angry."
Businessman Garvan O'Doherty, the owner of Da Vinci's Hotel, said the focus should remain on peace.
"The vast majority are focused on the partnership approach to peace. This will not detract those of us who want a stable society," he said.
He said young people who followed the bombers would "pay a high price in the future".
Mr O'Doherty said the way forward was for the peace process to continue.