President Obama was never in any danger because the party crashers went through the same security screening for weapons as the 300-plus people actually invited to the dinner honoring Indian Prime Minister Manmohan Singh, Donovan said.

Donovan confirmed the identities of the couple. The Washington Post, which first reported on their evening out, said the Salahis are well-known in the Virginia horse-country set and were being considered for the Bravo reality TV show Real Housewives of D.C.

In an interview with the CBS Early Show in September, Michaele Salahi said, "President Obama has made it very accessible for anyone to visit the White House, so that's like a big thing right now."

The CBS interview was part of a segment on potential candidates for Real Housewives of D.C. but never was aired.

The Secret Service learned about the security breach Wednesday after a media inquiry prompted by the Salahis' online boasts about having attended the private event, Donovan said.

One of the many photos from the dinner posted on Michaele Salahi's Facebook page shows the couple with a smiling Vice President Joe Biden. In other photos, they appear alone or together with White House chief of staff Rahm Emanuel, Washington Mayor Adrian Fenty, CBS News anchor Katie Couric, Rep. Ed Royce (R-CA), and three Marines in their dress blues.

Donovan would not comment on whether the couple had been contacted by the Secret Service, how long they were on the White House grounds or other details of the investigation.

The Post said uninvited guests who got in could face a potential trespassing charge unless someone from inside the White House staff slipped them in.

Donovan would not comment on possible legal violations.

The agency's Office of Professional Responsibility is reviewing the incident. An initial finding indicated that a checkpoint did not follow proper procedures to ensure the two were on the guest list, Donovan said.

"It's important to note that they went through all the security screenings — the magnetometer screening — just like all the other guests did," Donovan said. And, he added, Obama and others under Secret Service protection had their usual security details with them at the dinner.