LONDON — A Royal Air Force base in Britain used by the U.S. Air Force was briefly locked down and a man was taken into custody after a disturbance Monday, police said. American service members fired shots, according to county police.

No one was injured other than the detained man, who had cuts and bruises. The nature of the disturbance was unclear, though British media reported that a car tried to ram the gates.

The U.S. has air-refueling assets stationed at the RAF Mildenhall base in Suffolk, about 80 miles north of London.

The base is home to the U.S. Air Force’s 100th Air Refueling Wing, which is responsible for American refueling operations across Europe. Other units, including the 501st Combat Support Wing, the 352nd Special Operations Wing and the 95th Reconnaissance Squadron are also stationed there.

The Pentagon urged all individuals near the base to avoid it, but the lockdown was lifted about an hour after the incident started.

The air base was scouted out in 2015 by an Islamic extremist who eventually received a life sentence for plotting an attack against U.S. military personnel.

Junead Khan was tried for using his job as a delivery driver to study RAF Mildenhall.

Authorities have not said if the incident at Mildenhall was suspected to be terror-related. Details have not yet been released.

A jury convicted Khan last year of planning to travel to Syria as a support of the Islamic State group and preparing possible attacks at Mildenhall and a second English base, RAF Lakenheath.