Londonderry, Northern Ireland (CNN) Police in Northern Ireland have released CCTV footage of a car bombing that shook central Londonderry on Saturday night.

In one of the four videos that were posted on the Police Service of Northern Ireland's Twitter, a group of young people can be seen walking past the vehicle minutes before the explosion.

Police release CCTV footage of explosion outside courthouse on Bishops Street in Derry/Londonderry last night. pic.twitter.com/tqzqBdCZnv

Four men have been arrested in connection to what police suspect to be an attack by the "New IRA."

Assistant Chief Constable Mark Hamilton told reporters: "For this investigation, our main line of inquiry is against the New IRA. The New IRA, like most dissident Republican groups in Northern Ireland, are small, largely unrepresentative and just determined to drive people back to somewhere they don't want to be."

The police confirmed in their statement that at least two armed men hijacked a pizza delivery car and installed a bomb inside, which was then driven to the location before it was detonated.

In two clips released by the police, the car can be seen stopping before the driver jumps out and runs away.

Hamilton described the attack as "a callous act, a deliberate act against the people of Derry and against the local police service. A deliberate attempt to harm this community and one we must all condemn."

The police also posted on Facebook that a second suspicious car was checked. "Now we're just dealing with an extensive crime scene," police said.

John Boyle, the mayor of Derry/Londonderry posted on Twitter : "Absolutely appalled by this terrible act of violence tonight right in the heart of our city. I utterly condemn this attack which could easily have resulted in loss of life or injury. The perpetrators do not speak for the people of Derry and Strabane!"

#Derry #Londonderry #NorthernIreland Police closed street in center city - "suspect car bomb" exploded - level of violence unseen here in years pic.twitter.com/I3tHr8vp16 — Nic Robertson (@NicRobertsonCNN) January 19, 2019

Police said it appeared that nobody was hurt in the attack.

'We have lived through this before'

Gina McFeely said she was in her flat, getting ready to go to her nephew's 21st birthday party, when she heard a loud bang.

"Everyone in the neighborhood came out into the street," she said. "Then I saw the car in flames, flames going up, and I said, 'Oh my God!' It's been a long time since a bomb went out in Derry. It was a shock."

Despite the explosion, she went ahead to the party.

"It doesn't make me afraid -- I am from Derry, we have lived though this before -- but it makes me angry," McFeely said. "We don't want to go back to this."

On scene in Derry/Londonderry where police say a suspected car bomb exploded in Bishop Street - incidentally meters away from the hotel where our crew stayed last night. pic.twitter.com/Xo3UxgICdD — Milena Veselinovic (@M_Veselinovic) January 19, 2019

A history of violence

Ireland's Deputy Prime Minister Simon Coveney condemned the car bombing, tweeting, "There is no place and no justification possible for such acts of terror, which seek to drag Northern Ireland back to violence and conflict."

The bombing raised fears that sectarian violence might be revived in Northern Ireland, which has been split over the question of whether to remain part of the United Kingdom or become part of Ireland.

More than 3,500 people died in the decadeslong conflict known as "the Troubles." The Good Friday, or Belfast, Agreement of 1998 was a turning point for the region ending years of bloodletting.

In recent years, the two main political parties -- the Democratic Unionist Party and Sinn Fein -- had worked together in a power-sharing executive, but it collapsed in 2017 and despite extensive talks has yet to be restored.

Even the name of the city has been disputed, with nationalists, who are in favor of a united Ireland, calling it Derry and unionists, who want to remain part of the United Kingdom, calling it Londonderry.

The city has a population of about 240,000 in its metro area. It's about 112 kilometers (70 miles) west of Belfast.

Politicians react

Sinn Fein MP Elisha McCallion posted on the party website, "This incident has shocked the local community," she said. "In particular, there are many elderly residents who live in the area who have been alarmed by this incident."

Democratic Unionist Party leader Arlene Foster used her official Twitter page to thank emergency services for their quick action "which helped ensure there have been no fatalities or injuries."

"This pointless act of terror must be condemned in the strongest terms. Only hurts the people of the City. Perpetrated by people with no regard for life," she said.