Folk-rock legend David Crosby is in hot water after firing off a tasteless tweet cheering on Saturday evening’s deadly inferno at Trump Tower.

“[O]h boy ……burn baby burn,” wrote the ‘60s music icon in a since-deleted post as the fatal blaze raged on the 50th floor of the Fifth Avenue high-rise, screenshots of the offending tweet show.

Though the message didn’t specifically mention Trump Tower, when fellow user @JeffreyGuterman tweeted Crosby asking if he was referencing the blaze, the 76-year-old folkie replied, “yes Jeffrey,” screenshots show.

Art dealer Todd Brassner, 67, was killed in the four-alarm inferno, and four firefighters were injured.

Backlash to the crass tweet was swift on social media.

“Nice that you are happy when people are hurt,” wrote user @NYCEMSwatch.

User @ThePowersThatBe chimed in, “A relic from the ‘peace & love’ generation weighed in on the Trump Tower fire predictably, albeit temporarily.”

“#TeachYourChildenWell,” he added, referencing the title of a 1970 hit by Crosby, Stills, Nash & Young.