AMESBURY, England -- In this normally pleasant town of 10,000 residents a stone's throw from the mysterious Stonehenge monument, the new reality is sinking in: Novichok, again.

Four months had passed since the nerve-agent attack on a former Russian spy and his daughter, and the collective nightmare seemed to be fading. No longer were forensics experts in oversize hazmat suits combing the area for an invisible killer developed by the Soviet Union in Cold War times.

Eager tourists, drawn by an unusually long spell of glorious summer weather, were back at Stonehenge, and England's World Cup team was surging, buoying spirits. Then a local couple with no obvious connection to Russia or to espionage fell desperately ill and the government said Novichok was to blame.

Some are embracing the "keep calm and carry on" ethos England displayed to manage through two world wars, but others were frightened by the seemingly random poisoning of two innocents who now lie critically ill in a local hospital.

"It's shocking, and it's scary," said Elaine Read, a worker at The Kings Arms pub who used to occasionally share a pint with Dawn Sturgess, one of the victims. "Nobody expected it to happen again. Everyone was saying it was Russia, but now it's just two ... local people. They're just like us."

She said it's difficult to feel safe after what happened to Sturgess, 44, and 45-year-old Charlie Rowley. Both became violently ill within hours of each other Saturday. At first, authorities believed they had taken some bad heroin or crack cocaine, but it turned out to be Novichok.

"You don't know where it is, that's the trouble," Read said of the elusive nerve agent. "You don't know how Dawn and Charlie got it, how it crossed their paths."

The bizarre case, combining elements of a murder mystery and a spy thriller, is stoking international tensions ahead of next week's NATO summit, which will deal in part with worsening relations between Russia and the West.

Britain's interior minister demanded Russia explain how two people were inadvertently poisoned with the same military-grade nerve agent used to attack ex-Russian spy Sergei Skripal and his daughter, Yulia, in the nearby town of Salisbury in March.

Britain has accused Russia of being behind the attack on the Skripals, which the Kremlin vehemently denies. British Home Secretary Sajid Javid told Parliament on Thursday it is now time for Russia to explain "exactly what has gone on."

"It is completely unacceptable for our people to be either deliberate or accidental targets, or for our streets, our parks, our towns to be dumping grounds for poison," Javid said.

In Amesbury, residents were advised to wash their clothes and take other precautions if they were at the locations believed to have been frequented by the latest victims.

Some were staying inside to avoid any risk of contamination, but most were going about their business. A few parts of town remained cordoned off by police, including the Baptist Church, but activity in the easygoing town center continued unabated.

"I'm not so easily scared, but there has to be more to it," said Justin Pritchard, enjoying a beer with a friend.

"We don't know what's going on. First, they said it was the Russians. Now this is completely separate. Originally, we all thought it was the Russians, now it doesn't seem quite right," he said, noting Sturgess and Rowley have no connection to Russia.

British officials said Thursday they believe the latest victims were not deliberately targeted but came into contact with the Novichok used in the Skripal poisoing. Police said the couple was exposed to the nerve agent after handling a contaminated item, but provided no details.

That isn't convincing to Rick Bird, 65, a retired British army veteran who was trained in the handling of nerve agents during his military career. He said he never dreamed nerve agents would be deployed in Britain.

"The latest case seems to be an odd one," Bird said. "The first one in Salisbury, we thought we were all over it. This came totally out of the blue. It's the fear factor, for everybody."

The last few days have been traumatic for some residents, particularly those who live close to areas shut down to the public because of possible contamination.

Alex Brittany, 29, said he woke up to find the Baptist Church near his home being cordoned off. The experience left him shaky.

"It is quite frightening," he said. "What scared me this time was that the cordons were near where I live. You expect big attacks in London, Manchester. But Amesbury? Salisbury? Wow. Really?"

Experts say just a few milligrams of the odorless Novichok liquid -- the weight of a snowflake -- is enough to kill a person within minutes. And finding it is the problem.

Chemical weapons expert Hamish de Bretton-Gordon said the latest victims were likely collateral damage from the Skripal attack.

"The Novichok gel that was smeared on the handle of the Skripals' house was presumably transported in some device or syringe," he said. "I think the working assumption now is that device or that syringe is what has appeared, and the residue caused these two people to become ill."

President Vladimir Putin's spokesman, Dmitry Peskov, said Russia is concerned about the case but had nothing to do with either poisoning.

"Russia has categorically denied and continues to categorically deny the possibility of any kind of involvement with what was happening there," Peskov told reporters Thursday.