Former Attorney General Beau Biden is being treated at a military hospital outside Washington, D.C.

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Vice President Joe Biden’s oldest son, Beau Biden, has been hospitalized at Walter Reed Army Medical Center outside Washington, D.C., the vice president’s office told PEOPLE in a statement Tuesday.

Beau, 46, a former Delaware attorney general who is running to be the state’s governor next year, is being treated at the military hospital in Bethesda, Maryland.

No further details were available, but a source close to the Biden family tells CNN the situation is “serious.”

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The vice president’s son, who served in Iraq as a captain in the Delaware National Guard, has a history of medical problems. He suffered a minor stroke in 2010, and in 2013 he was admitted to the hospital after falling ill while on vacation. He was later diagnosed with a brain lesion, and underwent surgery at a cancer center in Texas in 2013.