Six British soldiers killed in Afghanistan Tuesday died after their Warrior armored vehicle was hit by a very large Taliban bomb, reports indicated.
According to the BBC's Orla Guerin it must have been a well-placed massive explosion to damage the heavily armored vehicle.
The incident marks the worst single loss of British troops in the country since 2006.
Their families have been notifed of the deaths.
The British Warrior vehicle was traveling over unpaved roads in the Nar-e-Saraj area of the province, where British troops have been training local police officers and security forces for about a year, according to CNN.
The BBC's Quentin Sommerville noted the device must have been extremely well placed in order to cause the Warrior such catastrophic damage.
Including the six, a total of 404 Britons have died in Afghanistan since the invasion in 2001.
It is a reminder of the huge price that we are paying for the work we are doing in Afghanistan and the sacrifice that our troops have made and continue to make, British Prime Minister David Cameron told the BBC.
I do believe it's important work for our national security right here at home but of course this work will increasingly be carried out by Afghan soldiers and we all want to see that transition take place.
The UK has 9,500 soldiers in Afghanistan, a number that will decrease incrementally as the 2014 troop withdrawal date nears.
Lieutenant Colonel Gordon MacKenzie, spokesman for Task Force Helmand, said in a statement:I have the tragic duty to report that six soldiers are missing, believed killed, during a security patrol. The six soldiers, five from 3rd Battalion The Yorkshire Regiment and one from 1st Battalion The Duke of Lancaster's Regiment, were on patrol in a Warrior armoured fighting vehicle when it was caught in an explosion in the Task Force Helmand Area of Operations.