Democratic Sen. Edward Kennedy was recovering in a Washington hospital Tuesday evening after he collapsed at a luncheon for U.S. President Barack Obama.
Sen. Orrin Hatch, who accompanied Kennedy to the ambulance, said it "looked like a seizure" had stricken the brother of late president John F. Kennedy.
Kennedy, who turns 77 next month, was diagnosed with a brain tumour last May.
Later in the afternoon, Kennedy was conscious and talking to medical staff at the Washington Hospital Center.
"After testing, we believe the incident was brought on by simple fatigue," said Dr. Edward Aulisi, head of neurosurgery at the hospital, in a statement released by Kennedy's office.
"He will remain ... overnight for observation, and will be released in the morning,"
The statement added that Kennedy "is awake, talking with family and friends, and feeling well."
Democratic Sen. Christopher J. Dodd said that Kennedy did have a seizure during the luncheon, but appeared to be feeling better even as he was taken to the ambulance.
"The good news is, he's going to be fine," Dodd said, who added that the incident "took a lot out of" Kennedy.
Dodd noted that as Kennedy was being put in the ambulance, he said "I'll be OK, I'll see you later."
Meanwhile, Democratic Sen. Robert Byrd was also taken from the luncheon, however, it's still not clear if his departure was due to a medical issue.
The 91-year-old senior senator from West Virginia has seemed frail and unhealthy over the past few weeks.
During an address to members of Congress and others, Obama said his prayers were with Kennedy and his family.
"I know that while I was out of the room, concern was expressed about Teddy," said Obama, adding that Kennedy continues to be a long-serving advocate for democracy and justice.
Obama said that Kennedy "was there when the voting rights act passed, along with John Lewis."
Obama added that Kennedy has been "a warrior for justice."
Kennedy was seen being taken from the Statuary Hall in the Capitol by wheelchair, CNN reported.
Kennedy suffered a seizure in May 2008 and later underwent surgery in June for a malignant brain tumour.
After undergoing weeks of chemotherapy and radiation treatment last year, he began to make more public appearances.
"And so I would be lying to you if I did not say that right now a part of me is with him," said Obama of Kennedy.
"And I think that's true for all of us. This is a joyous time. But it's also a sobering time. And my prayers are with him."
With files from The Associated Press
