Anita Woolnough was setting off for an early morning dog walk at 05:25 on Sunday when she first spotted police activity.
By the time she returned, she said there were about 50 police vehicles in the area.
“There were loads of police here,” she said. “Armed police and they were shutting down the event”.
She added she was pleased to hear police were expected to stay at the scene for the next few days.
Jason Langford, who lives at Great Blakenham, said: “I’m still reeling from it, quite honestly. You just don’t expect it in rural Suffolk.
“I was amazed by the armed police, the road closures – it was absolute carnage.
“They [the police] handled it really well, very calm, very methodical… You don’t normally see that in a little village like this; it’s very peaceful, but they handled it really well.
“Then a few of my neighbours started to come out to understand what was going on, but at that time we didn’t know of the terrorist threat, which is probably not a bad thing, as otherwise people start speculating.”