UPDATE: A rep for the Spears family has released the following statement:
"Jayden James Federline was admitted to the Southwest Mississippi Regional Medical Center on Sunday, November 9th. Doctors concluded he had a reaction to something he ingested. He is expected to be discharged tomorrow."
Britney Spears made an unexpected trip to the hospital over the weekend, but this time it wasn't the pop star's health that was the issue.
Instead, E! News has learned that Spears' youngest son, Jayden, was rushed to the emergency room by the pop star sometime between 2 p.m. and 3 p.m.
"She looked very stressed," an eyewitness told E! News.
A short time later, Spears' sister, Jamie Lynn, arrived at the hospital after being driven by a friend.
Spears herself drove the 2-year-old to the hospital instead of waiting for an ambulance. While there's no official word on the reason for Jayden's admittance, the tyke spent Sunday night at the facility under observation.
Britney was spotted leaving Southwest Mississippi Regional Medical Center—the same hospital, coincidentally, where Jamie Lynn gave birth this year—earlier this morning, but it was not clear whether Jayden had been discharged.
Britney's brother, Bryan, and her other son, Sean Preston, accompanied by a nanny, were also seen exiting the medical center today. Last night, the elder Spears was spotted bringing fast food into the hospital.
Britney, Jayden and Sean were expecting to spend a leisurely weekend with family in the pop star's hometown of Kentwood, La., the first time since her January meltdown that 26-year-old singer was allowed to take the boys out of California. The family only arrived on Friday.
A source close to the family told E! News that Kevin Federline has been made aware of his son's hospitalization and will fly out to the Mississippi facility should the boy not be discharged today.
—Additional reporting by Tina Dirmann and Claudia Rosenbaum
(Originally published on Nov. 10, 2008, at 9:16 a.m. PT.)