A stolen vehicle was driven onto the runway of the main British base in Afghanistan then burst into flames as US Defence Secretary Leon Panetta arrived there today.
The incident at Camp Bastion in Helmand Province is believed to be linked to an earlier incident, which left a British serviceman with minor injuries.
Mr Panetta arrived at the base to meet troops, commanders and Afghan government officials, just days after a US soldier went on a deadly shooting spree in Kandahar.
Around the same time as the defence secretary's aircraft landed, a vehicle got onto the runway at Camp Bastion and caught fire.
The driver, a local man employed at the base, is being treated at Camp Bastion's hospital for his injuries, according to a spokeswoman at the camp.
The base is home to a large contingent of US troops as well as UK forces.
A statement from Isaf said: "Isaf is aware of a stolen vehicle incident today at Camp Bastion, which resulted in the injury of one coalition service member.
"The alleged perpetrator was apprehended by base security personnel. We are currently investigating to determine more facts.
"This incident took place this afternoon around the same time US Secretary of Defence Leon Panetta was arriving in Afghanistan.
"At no point was the Secretary or anyone on the aircraft in any danger from this incident."
Camp Bastion was put under "lockdown" in the aftermath of the incident, with flights and movements in and out restricted while it was investigated.
Ministry of Defence police patrolled roads inside the base in the wake of the incident.
A spokeswoman at Camp Bastion said: "Procedures were put in place to account for the whereabouts of all military and civilian personnel and, to achieve this, movement within Camp Bastion was restricted."
The incident comes amid increasing tension between Isaf forces and Afghan locals.
At the weekend 16 Afghan civilians, including several children, were shot dead by a US soldier.
Last month there was anger after US troops burned Korans on an American base.
Mr Panetta's two-day visit is scheduled to include meetings with President Hamid Karzai, Afghan defence officials and provincial leaders, as well as routine discussions with his commanders on the ground.
Asked about the incident at a White House press conference with US President Barack Obama, Prime Minister David Cameron said it was not yet clear exactly what had happened.
"It is very early details still coming through. Obviously we will want to examine and investigate exactly what has happened before making clear anything about it," he said.
"But the security of our people, of our troops - the security of both our nation's forces - is absolutely the priority.
"If there are things that need to be done in the coming hours and days to keep them safer, be in no doubt we will do them."