Police searching the home of a British family found shot dead in the French Alps last week evacuated neighbouring properties on Monday after saying they had discovered unspecified items that had caused them concern.
Television footage showed a bomb disposal vehicle outside the home of Saad al-Hilli, the Iraqi-born British engineer who was shot twice in the head along with his wife, her mother, and a passing French cyclist.
French media had reported that British police were focusing their investigation on Hilli's work as a mechanical engineer.
Detectives have refused to comment on British media reports that Hilli was known to security services and was under police surveillance during the second Gulf war.
Earlier officers had sealed off the road in the leafy village of Claygate in Surrey, southwest of London, and began removing neighbours living close to Hilli's 1 million pound ($1.60 million) detached house.
"Surrey Police can confirm that due to concerns around items found at the address in Oaken Lane, Claygate, officers have extended the cordon surrounding the property," a spokeswoman said.
"Neighbours in the immediate area are being evacuated," said the spokeswoman who gave no details as to what had caused the alarm. "It's happening quite rapidly and we're trying to get a grasp on what we're dealing with," she said.
Monday's search was the latest development in a shooting on a remote forest road last Wednesday near the French village of Chevaline that has dominated media headlines in Britain and generated much speculation as to the motive.
Hilli, a mechanical engineer who contracted with Surrey Satellite Technology, a subsidiary of aerospace and defence firm EADS, and the other victims were shot twice in the head in what appeared to be execution-style killings.
His daughters, aged seven and four, survived the attack. The oldest girl Zainab, who suffered serious skull fractures, came out of a coma on Sunday and will be questioned as to what happened as soon as she is able to, a French prosecutor said.
Her younger sister Zeena survived the shooting unscathed and both girls are under police protection.
French State Prosecutor Eric Maillaud said a family feud over money was one of several motives still being considered as a motive for the murders and Hilli's brother had been formally questioned. The brother has denied any dispute with Hilli.
French media also said British police were investigating Hilli's work rather than his family.
He helped to design the kitchen of the European Airbus aircraft, specialising in computer-aided design and mostly working from his home in Claygate, according to Julian Stedman, his accountant since 2004.