May 17 (HealthDay News) -- Massachusetts Sen. Edward M. Kennedy was taken from a local hospital near the Kennedy family compound on Cape Cod to Massachusetts General Hospital in Boston early Saturday after suffering from at least one seizure, and possibly a second one, according to news reports.

Kennedy, 76, was "resting comfortably" at the hospital, according to an early afternoon news release from his office. The news release confirmed that Kennedy, the second-longest serving Democratic senator currently in Congress, had suffered a seizure.

"It appears that Senator Kennedy experienced a seizure this morning," the press release said. "He is undergoing a battery of tests... to determine the cause of the seizure... It is unlikely we will know anything more for the next 48 hours."

Later in the afternoon, according to the Associated Press, Kennedy's spokeswoman Stephanie Cutter said he was "conscious, talking, joking with family."

She added that Kennedy did not appear to have had a stroke as initially suspected.

According to the Boston Globe, a government official who accompanied the senator on the helicopter trip from Hyannisport to Boston said that Kennedy had experienced a second seizure during the ride. The report of a second seizure had not been confirmed by medical experts or Kennedy's office late Saturday afternoon.

His son Edward arrived at the hospital at about 1 p.m., the newspaper said, and his daughter, Kara, arrived about an hour later. His wife, Victoria, was at his bedside, the Globe reported, and his senatorial colleague from Massachusetts, John Kerry, also came to visit, as did his nephew, former Congressman Joseph P. Kennedy.

In October 2007, a partially blocked carotid artery in Kennedy's neck was discovered during a routine magnetic resonance imaging (MRI) examination. Doctors cleared the blockage, and Kennedy was released to convalesce in Hyannisport. The Globe reported at the time that the blockage could have caused a stroke, but that the chief of vascular surgery at Massachusetts general described the procedure as "routine, uneventful, and successful."

According to the John F. Kennedy Memorial Library, Sen. Kennedy's father, former U.S. Ambassador Joseph P. Kennedy, suffered a series of strokes in 1961 at the age of 73. The thromboses left him virtually paralyzed and unable to speak. He died in 1969.

According to the National Health Library, a stroke occurs once every 45 seconds in the United States. Strokes happen when a blood vessel carrying blood to the brain is blocked by a blood clot. This is called an ischemic stroke. When a blood vessel breaks open, causing blood to leak into the brain, a hemorrhagic stroke occurs.

Kennedy is the youngest of 9 children, and became a U.S. senator in 1962. His older brother, John F. Kennedy, who was elected president in 1960, was assassinated in 1963. Robert Kennedy, who was also a U.S. Senator, was assassinated in 1968 during his presidential campaign.

SOURCES: Boston Globe, May 17, 2008; Office of Sen. Edward M. Kennedy, D-Mass., press release, May 17, 2008; Associated Press; John F. Kennedy Memorial Library