Red Hot Chili Peppers performs at The Isle of Wight Festival at Seaclose Park on June 14, 2014 in Newport, Isle of Wight.

The singer was suffering from extreme stomach pain.

Red Hot Chili Peppers frontman Anthony Kiedis was sent to an area hospital hours before a headlining slot at KROQ's annual Weenie Roast on May 14. Flea made the announcement from the stage at Irvine Meadows Amphitheatre and apologized on behalf of the band telling the crowd at the 16,000-capacity venue that they were "devastated."

According to a rep for the Los Angeles radio station, Kiedis was taken from the venue in an ambulance suffering from extreme stomach pain.

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Weezer ended up closing the show, which was held in Irvine, Calif. Red Hot Chili Peppers were due to take the stage at just after 10 p.m. local time. At 10:30p.m., KROQ tweeted that "due to illness, the Chili Peppers were forced to cancel their set."

Unfortunately due to illness the @ChiliPeppers were forced to cancel their set tonight at #WeenieRoast. More details to come. — KROQ (@kroq) May 15, 2016

Other bands on the bill included Panic! at the Disco, Empire of the Sun, Garbage, Lumineers, Fitz and the Tantrums and Miike Snow. Blink-182 also performed a surprise set.

RHCP drummer Chad Smith tweeted how disappointed the band was they couldn't perform, in addition to wishing "a speedy recovery to my brother Anthony."

NO one's more disappointed than us that we couldn't perform tonight. Sending love and a speedy recovery to my brother Anthony. — Chad Smith (@RHCPchad) May 15, 2016

Billboard has reached out to reps for the Chili Peppers for comment.