According to WBAL, the Maryland Democrat died about 2:45 a.m. Thursday at Johns Hopkins Hospital in Baltimore "due to complications concerning longstanding health challenges," his office said in a statement.
The news came one day after the Baltimore Sun reported that Cummings had not returned to Washington after having a recent "medical procedure." His office did not share details about the procedure.
Cummings, who represented Maryland's 7th District for more than 23 years, was the chairman of the House Oversight and Reform Committee. The Sun described him as "a key figure in the impeachment inquiry into President Donald Trump."
Trump shared condolences for Cummings' family in a statement released Thursday morning.
"I got to see first hand the strength, passion and wisdom of this highly respected political leader," he said. "His work and voice on so many fronts will be very hard, if not impossible, to replace!"
Former President Barack Obama said in a statement that he and his wife, Michelle Obama, were heartbroken by news of Cummings' passing.
"As Chairman of the House Oversight Committee, he showed us all not only the importance of checks and balances within our democracy, but also the necessity of good people stewarding it," Obama said. "Steely yet compassionate, pricinipled yet open to new perspectives, Chairman Cummings remained steadfast in his pursuit of truth, justice, and reconciliation."
Flags were lowered Thursday on Capitol Hill to honor Cummings, Cox Media Group's Jamie Dupree reported.
"I'm devastated by the loss," House Speaker Nancy Pelosi said Thursday after meeting with Cummings' wife to share condolences from her caucus. "She said what we all knew -- he just fought to the end. But that's the way he was."
According to Cummings' congressional website, the Baltimore native graduated from Howard University with a bachelor's degree in political science before completing law school at the University of Maryland. He eventually was awarded 13 honorary doctorates, the website says.
Before he was elected to the U.S. House of Representatives, Cummings was a member of the Maryland House of Delegates from 1983 to 1996. Cummings' website says he was "the first African American in Maryland history to be named speaker pro tem."
Cummings is survived by his wife, Maya Rockeymoore Cummings, and three children, the Washington Post reported.
After learning of his death, friends, colleagues and other public figures remembered Cummings on Twitter, calling him a "patriot" and a "warrior."