Feb. 27 (Bloomberg) -- Saudi Arabian authorities don't rule out terrorism in the killing of four Frenchmen, including two Schneider Electric SA employees, in the kingdom, holder of the world's largest oil reserves.

``We're treating the attack as a criminal act, but terrorism is not eliminated as a motive,'' Interior Ministry spokesman Lieutenant-General Mansour al-Turki said in an interview. The toll rose to four today, when a 17-year-old boy died of injuries sustained in yesterday's shooting, Mutawakel al-Hagag, a doctor at King Fahd Hospital in the Muslim holy city of Medina, said.

The attack raises fears of a return of terrorism to Saudi Arabia, which has battled members of Osama bin Laden's al-Qaeda network since 2003. The last major incident was in February last year when a suicide attack was foiled at the largest Saudi oil- processing center in Abqaiq in the east of the country.

Schneider Electric, the world's largest maker of circuit breakers, said it `` stopped all movement of people'' into and around Saudi Arabia, the company's vice president in Saudi Arabia, Jean-Claude Abesca, said by telephone from Riyadh.

The world's largest oil company, Saudi Aramco, said security at its installations is always high.

Foreign companies ``will be shaken, but it won't influence their long-term investment plans,'' Mustafa Alani, director of national security at the Dubai, United Arab Emirates-based Gulf Research Center, said in a telephone interview.

`Short-Lived' Impact

``The impact will be short-lived, because over the past three years, there has been a reduction in the number and quality of attacks,'' he said.

Schneider Electric in 2005 signed a $30 million power supply contract with Saudi Arabian Basic Industries Companies, the world's largest petrochemicals producer.

The French group of three men, the 17-year-old boy, three women and two children, was attacked yesterday by unidentified gunmen on a desert road in western Saudi Arabia. Two of the men were killed instantly, al-Turki said.

``We can never count out terrorism,'' al-Turki said.

The French Foreign Ministry wouldn't speculate on the motives for the attack.

``We cannot qualify this attack, it could be anything and we cannot assert anything at this stage,'' a spokeswoman, who declined to be named according to ministry regulations, said in a telephone interview.

The U.S. Embassy in Riyadh is ``examining what happened and talking to Saudi authorities,'' Melissa Ford, the embassy's information officer said from Riyadh.

To contact the reporters on this story: Tarek Al-Issawi in Dubai at talissawi@bloomberg.net; Glen Carey in Dubai at gcarey8@bloomberg.net

Last Updated: February 27, 2007 05:40 EST