A man was arrested after a motorist reportedly tried to ram the gates of RAF Mildenhall and was fired upon by security guards.
The 44-year-old British man, who suffered cuts and bruises, was arrested on suspicion of criminal trespass in what police described as a ‘significant’ incident.
Suffolk Police have confirmed the incident is not being treated as terrorism.
The base was put into lockdown at 1pm and Suffolk Police were called at about 1.40pm.
A police spokeman said: “The base was put into lockdown and units responded immediately.
“Shots were fired by American service personnel and a man has been detained with cuts and bruises and taken into custody.
“Police are not looking for anyone else on the site in relation to the incident.
“There is no wider threat to the public or occupants on the base and no other people have been injured as a result of the incident.
“The incident remains a police investigation at this time and enquiries are on-going and police are receiving support from other law enforcement agencies.”
A spokesman for the base said: “Lockdown ended at 3.34pm on RAF Mildenhall and operations are returning to normal.
“We’ve concluded our combined US-UK response to this incident and we are continuing to support local authorities in the ongoing investigation.”
Mildenhall’s Great Heath Academy primary school, which is a few hundred metres from the base perimeter fence also went into lock down as soon as it was alerted about the incident.
Head Steven Vincent said: “For many years we’ve had a ‘reverse fire drill’ policy for what to do if there was anything at the base. If the children are outside we get them back in, the gates are locked, the doors are locked and we close the blinds.
“The police were in liaison with us throughout and advised us whether to let the children go at home time, but we were only three or four minutes late.”
Parents were informed via the school’s ‘parent mail’ email system and Mr Vincent praised parents and children for their co-operation.
He added: “We just carried on regardless, having made sure we were safe and secure – it was a very interesting day.”
West Suffolk MP Matt Hancock said: “I have been in contact with the base and Suffolk Police and Crime Commissioner Tim Passmore and I am being regularly updated to developments at RAF Mildenhall.
“We await further details, and I have the utmost trust in the professionalism of the servicemen and women at the base to protect us and to defend our national security.
“At moments like this it is important to reiterate how strongly we support our friends – American and British – who work and live on and around the base at Mildenhall. They defend our freedom and our values. The warmth of our welcome and the strength of our resolve will not be diminished, but instead enhanced, by incidents like today’s.”