Six British soldiers were believed killed after an explosion hit their armored vehicle in southwestern Afghanistan, Britain's Ministry of Defense said Wednesday. If confirmed, it would be the biggest loss of life for British forces in the country since a plane crash in 2006.

The soldiers were on patrol in Helmand province at the time of the blast on Tuesday evening. The military did not explain why they are unable to confirm whether the soldiers were killed.

"This tragic incident brings home to us the dangers that are faced on a daily basis by the men and women of our armed Forces deployed in Afghanistan," said Defense Secretary Philip Hammond said. "My thoughts are with the families and friends of the six soldiers who are missing, believed killed and also with their colleagues, both in Afghanistan and the UK, whose brave work continues or is about to start."