He reportedly suffered a seizure.
Obama said his prayers were with Kennedy -- the brother of former president John F. Kennedy -- and his family.
"I would be lying to you if I did not say that right now a part of me is with him," Obama said.
Kennedy, 76, suffered a seizure towards the end of the lunch, which occurred just after Obama was sworn in as president.
Kennedy was transported by ambulance to a local hospital. Our thoughts are with him now, and we will keep you posted as this story develops.