Washington ? Sen. Edward M. Kennedy, ill with a brain tumor, was hospitalized Tuesday but quickly reported feeling well after suffering a seizure at a post-inauguration luncheon for President Barack Obama.

“After testing, we believe the incident was brought on by simple fatigue,” Dr. Edward Aulisi, chairman of neurosurgery at Washington Hospital Center said in a statement released by the senator’s office.

“He will remain … overnight for observation, and will be released in the morning.”

The statement said the 76-year-old senator “is awake, talking with family and friends, and feeling well.”

The statement did not disclose the tests that were performed on Kennedy, whose seizure was witnessed by several fellow senators seated with him at lunch.

Sen. John Kerry, D-Mass., told reporters he and Kennedy’s wife, Vicki, grabbed the senator as he became ill.

Added Sen. Chris Dodd, D-Conn., “It took a lot out of him. Seizures are exhausting.”

Even so, Dodd quoted Kennedy as saying, “I’ll be OK, I’ll see you later” as he was put into an ambulance.

“The good news is he’s gonna be fine,” Dodd added.

Kennedy had appeared in good health and spirits a few hours earlier when he stepped out of the Capitol and onto the inauguration platform where Obama took the oath of office. His endorsement of the former Illinois senator had come at a pivotal point in the Democratic presidential race, and the older man campaigned energetically for the younger one.

Sen. Jay Rockefeller, D-W.Va., told reporters that Obama noticed when Kennedy became ill, and rushed over to his table.

“There was a call for silence throughout the room,” he said. “The president went over immediately. The lights went down, just to reduce the heat, I think.”

Sen. Robert C. Byrd, 91, also left the luncheon early, but his office and others said his health was not the reason.

Byrd “is currently in his own office … and is doing fine, though he remains very concerned about his close friend, Ted Kennedy,” said Mark Ferrell, a spokesman for the West Virginia Democrat.