BOWLING GREEN, Ky. — Sen. Rand Paul, R-Ky., is recovering from five broken ribs and bruises to his lungs, and it is unclear when he will return to Washington, D.C., aides said Sunday, signaling that injuries he sustained Friday are far more severe than initially thought.

The second-term senator and 2016 presidential candidate was allegedly attacked by a next-door neighbor, Rene Boucher, 59, who was charged with fourth-degree assault.

Paul made his first public comments since the incident on Sunday, tweeting that his wife “Kelley and I appreciate the overwhelming support after Friday’s unfortunate event. Thank you for your thoughts and prayers.”

The nature of the dispute between Paul and Boucher remained a mystery to locals who know both men as medical professionals based in this southwestern Kentucky town.

Paul is an ophthalmologist who has practiced in town since moving here with his wife in 1993. He continues to provide free medical care to low-income Kentucky residents when the Senate is not in session.

Boucher is an anesthesiologist and the inventor of the Therm-a-Vest, a cloth vest partly filled with rice and secured with Velcro straps that is designed to help with back pain. He has worked at several local medical facilities through the years, according to public health records.

David Ciochetty, a doctor with Interventional Pain Specialists in Bowling Green, said that Boucher worked there between 2010 and 2012 before leaving because of unspecified issues.

Boucher was being held on $5,000 bond, state police said.