Martine Groby rues the day when she ignored her father who told her: "They are terrorists, take down their number plates."
"I should have listened to him," said Groby, who saw all the windows of her home in Spain shatter when a massive explosion detonated in the house next door on Wednesday.
It turned out that house hidden behind olive trees was likely the bomb factory of suspected jihadists who used vehicles to mow down pedestrians in Barcelona on Thursday and the nearby seaside resort of Cambrils hours later.
It was in the small seaside town of Alcanar, about 200 kilometres (120 miles) southwest of the Catalan capital, where the cell was apparently plotting "one or more attacks" in Barcelona, said regional police chief Josep Lluis Trapero.
But they are believed to have accidentally detonated an explosion, which blew up at least two of them, and forced them to change their plans.
Investigators combing the site have uncovered 120 gas canisters, as well as detected traces of TATP -- the explosive of choice for the Islamic State organisation, which has claimed the assaults.
"It stank of gun powder. An impossible stench, I told police on the night of the explosion, but they didn't want to listen to me," complained Jenny Rodriguez, 37, who lives just across the road.
It was only after the double attack that killed 14 people that police drew a link to the Alcanar explosion.
In the small area of Alcanar blocked off by police, the streets are deserted and inhabitants silent.
The groan of air-conditioners working overtime in the searing summer heat and the barks of dogs are punctuated by explosions of gas canisters still buried in the bomb factory and the noise of police tractors removing rubble.
Ask locals walking through the district about the house and they say they have never seen or heard the "men who lived there".
Groby, a French national, however said she saw them often.
She comes only several times a year to her pink-painted villa but she noticed that four men "who all speak French" were in the house next door since April.
They told her they had rented the house.
"I called them squatters," she said.
"They were very discreet, too discreet. The shutters were closed, there was no music, no children, no women," she recalled.
"Sometimes they stay just two days and they leave. They said hello to me but never looked me in the eye," added the 61-year-old retiree.
She only caught glimpses of the men next door, but said she was able to identify two of the suspects in photos published in the media after the attacks.
But a friend who suffered cuts to his face in the explosion, had told her to stay out of it.
Eliane Fernandez, who was also there on Wednesday night, said "the boom" of the explosion still resonates, but did want to talk further.
Groby described the men as "Arab types", and said one of them had a moustache.
Only her husband and her daughter has seen the one "who wears a beard", she said.
"They were often on the terrace. From up there, they must have been watching the road," she said, sighing that it was only now that she is piecing together all the clues about her neighbours.
Groby also recalled that the men often went out in pairs while the two others would stay behind at home.
They would either go on foot with backpacks, drive in and out in a white Kangoo van, or use two motorcycles.
They would also "move in a manner so that I am unable to see what they are unloading," she said.
"One time, I managed to see them unloading a freezer," she recalled.
"My father who's a former police officer had told me they are terrorists. He told me to take photos and write down their licence plates."
"He found these daily to and fro trips strange. I didn't want to believe him," she said.
But as she began hearing noises of metal scraping in July and started seeing lights on at all times of the day, she began to ask questions about the house.
She finally found out it belonged to a bank which had put it up for sale.
On Wednesday, shortly after 11 pm, as she and her family were clearing away dinner, she was flung to the floor.
"Suddenly it became all black. I had the impression that I was being burnt alive... I thought it was a nightmare. I didn't know they were terrorists. I thought it was our gas canister that exploded," she said.
That was also want police thought initially, until the jihadists embarked on their twin assaults along the coast a day later.