Lynyrd Skynyrd have canceled their concert scheduled for tonight because of a "medical emergency" involving Gary Rossington. The 65-year-old guitarist is the band's only member from the original lineup.

According to the Tallahassee Democrat – the hometown Florida paper where Lynyrd Skynyrd were scheduled to perform tonight – the exact cause of the medical issue is not known.

Rossington has had at least two heart procedures within the past 18 months. The first was surgery in July 2016, when a series of band shows had to be canceled. He had another heart-related issue this past August. He suffered a heart attack in October 2015 that sidelined the band for a period.

The latest procedure from three months ago was performed to "address some blockage in his arteries to his heart." At the time, he was advised to stay off the road for a week.

Lynyrd Skynyrd have a long history with health-related issues, dating back to the period before and after the plane crash claimed the lives of several passengers and band members, including singer Ronnie Van Zant. In 1976, Rossington and Skynyrd's other original guitarist, Allen Collins, were involved in separate car crashes. After the plane crash, Rossington had to play with steel rods in an arm and a leg.

Collins was paralyzed after a 1986 car accident; he died four years later of respiratory failure. Bassist Leon Wilkeson died in 2001 at age 49 of natural causes. Keyboardist Billy Powell died of a heart attack in 2009. And singer Johnny Van Zant, who replaced his late brother in the band in the late '80s, denied heart attack rumors after more shows were canceled because of an unidentified "family emergency" late last year.

Lynyrd Skynrd have a few more Florida shows scheduled for this year, but so far there's no word on whether or not they will continue. Tickets for tonight's concert are being refunded.

UPDATE 11/4: Lynyrd Skynyrd have canceled this Sunday's appearance at Rock Fest 80's in Pembroke Pines, Fla. The festival's organizers wrote on Facebook that 38 Special will perform instead. "Stepping up to fill in for our rock & roll brothers Lynyrd Skynyrd," the band wrote.  

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