A statement on his Instagram account, verified by NBC News, said the artist died “unexpectedly.”

Ka performs at the Pitchfork Music Festival in Chicago on July 19, 2014.Barry Brecheisen / WireImage file

Celebrated New York City rapper and former firefighter Ka, whose real name was Kaseem Ryan, has died, according to his social media accounts. He was 52.

He passed away “unexpectedly” on Saturday, a statement on his Instagram account, verified by NBC News, said Monday. It praised his contributions to firefighting, to his beloved neighborhood of Brownsville and to hip-hop as part of a “life of service—to his city, to his community, and to his music.”

A cause of death was not available, and a spokesperson for the New York City chief medical examiner did not immediately respond to a request for information.

“Capt. Ryan served the FDNY and the people of the city of New York with distinction for 20 years, working assignments in both the Bronx and Brooklyn,” Fire Department spokesperson Jim Long said by email. “The Ryan family remains in our thoughts during their time of loss.” 

Ka’s artistry gained notoriety among critics, songwriters and fellow emcees relatively late in his life, as he first wowed audiences in 2008 with messages and music that existed almost entirely beneath the surface, in an indie-rap scene where charts and Ferraris have little currency.

Ka became known for his published lyrics and collaborations with the likes of GZA of Wu-Tang Clan and producer Roc Marciano. He maintained space in the heads of critics and fellow hip-hop artists for his humble, subtle and stinging rhymes, with some calling him one of the hip-hop’s greatest writers.

The track “$,” featured on Ka’s celebrated 2016 album, “Honor Killed the Samurai,” detonated mainstream hip-hop, describing it as celebratory in a time of metaphorical war.

“With bars of greed, I plead, how many cars you need? When fathers bleed to fill ribs of kids that hardly read/F— your loot rhymes, and the new finds you purchased/If you ain’t buyin’ no soup for them soup lines and churches,” he wrote.

In a 2016 profile headline, the music publication The Fader called Ka “New York Rap’s Greatest Living Treasure.” Hip-hop journalist Jeff Weiss said Monday on X that Ka was “the master of quiet rage,” whose music contained “pain, grief and wisdom in every bar.”

The announcement on Ka’s Instagram page said he produced 11 albums under his name. “He leaves an extraordinary legacy as a recording artist,” it said.

Ka’s story is rare on multiple levels, including his success later in life after he eschewed the recording studio in favor of a 20-year firefighting career that, according to the statement on his Instagram account, brought him to the historic tragedy of 9/11 as a first responder and ultimately saw him reach the rank of captain.

He told The Fader that a cousin gave him $1,000 in 1989 so he could purchase studio time. In 1994, Ka’s name first appeared on a record as he participated in a project by Natural Elements, a collective of emcees and hip-hop artists.

His microphone dreams faded, however, and it wasn’t until the 2000s that he returned to recording, eventually releasing “Iron Works” in 2008. He told Complex magazine that he was inspired to show his mother he hadn’t wasted his youth trying to be a rapper.

“I wanted to give my mother a CD to put in her hand,” he’s quoted as saying. “I just wanted to prove that I didn’t waste 20 years of mastering a craft without anything to show for it.”

According to the music publication Pitchfork, that was also the year Ka’s reputation as a poetic emcee made its way to fellow Brooklyn native GZA (Gary Grice) of Wu-Tang Clan. GZA invited him to rhyme on the track “Firehouse,” featured on GZA’s “Pro Tools” album. Ka’s turn behind the mic with GZA seemed to certify his status as a low-key legend.

The track preceded a number of solo productions that put Ka’s name in circulation as a top lyricist. His last known recording, “The Thief Next to Jesus,” was released in August.

Ka is survived by his wife, his mother and his sister, according to the statement on his Instagram account.

In a statement on her verified Instagram account Monday, his wife, Mimi Valdes, called Ka “My king, my hero, my best friend.”