WASHINGTON — The computer phishing attack that Google says originated in China was directed, somewhat indiscriminately, at an unknown number of White House staff officials, setting off the Federal Bureau of Investigation inquiry that began this week, according to several administration officials.

It is unclear how many White House staff members — or those of other departments in the executive branch — might have been affected, according to two officials with knowledge of the investigation. But the intended victims ranged across various functions in the White House, and were not limited to those working on national security, economic policy or trade areas that would be of particular interest to the Chinese government.

Administration officials said they had no evidence any confidential information was breached, or even that many people fell for the attack by providing information that would allow a breach of their Gmail accounts.

White House classified systems run on dedicated lines and information on those systems, the officials said, cannot be forwarded to Gmail accounts. But investigators were trying to determine if the attackers believed that some staff members or other officials used their personal e-mail accounts for confidential government communications.