People whose lives were affected by the Buncefield oil depot blast are marking its first anniversary with a series of commemorative events.
A leak from a petrol tank at the depot near Hemel Hempstead in Hertfordshire triggered a series of massive explosions which devastated surrounding homes and businesses.
Community leaders and firefighters are gathering at the Leverstock Green cricket pitch near the site for a tree dedication ceremony. Business figures are taking part in the relaunch of the Maylands Business Park which suffered millions of pounds of damage in last year's blast.
Later, a prize-giving ceremony will be held for local schoolchildren who took part in a Buncefield art competition.
The first event - at 6am, about the time of the first explosion a year ago - is involving speeches by Daniel Zammit, chief executive of Dacorum Borough Council, and the mayors of Dacorum and St Albans.
The massive explosion was the biggest of its kind in peacetime Europe. It left two people seriously injured. A thick black smoke plume from the fire was visible across the south-east of England.
One year on, hundreds of people whose homes were damaged are still trying to claim compensation.
The devastating fire at the depot started when unleaded motor fuel being pumped into a storage tank overflowed, creating a lethal oil and air vapour. The malfunction was not noticed until the vapour ignited causing the first of several huge explosions. Firefighters battled for days to extinguish the ferocious blaze.
Many people living nearby are still counting the cost of the explosion and its aftermath. Mother-of-seven Heidi Brazier said her family is still living in a hotel and will not be home in time for Christmas as repairs continue on their house.
She said: "One woman said to me if she had the choice between compensation and turning the clock back she would say 'keep the money'. The suffering of some of those affected has been terrible and unreasonable."
