Photo may have been deleted

Screenshot: CBS News

CBS News issued a sincere apology on Monday night for mixing up photos of the late Congressman Elijah Cummings and U.S. Rep. John Lewis, who announced he has stage 4 pancreatic cancer.

The mixup occurred on Monday's broadcast of CBS Evening News. A photograph of Cummings was mistakenly identified as Lewis. Cummings died of natural causes on Oct. 17, at age 68.

"Tonight on the 6:30 p.m. ET broadcast of the CBS Evening News, one photograph was misidentified as Congressman John Lewis. We have replaced the photo in all broadcasts and platforms. We deeply regret the error," CBS tweeted.

News of Lewis' cancer diagnosis prompted reactions from celebrities and lawmakers on social media.

Lewis, 79, said he will continue to serve in the House of Representatives while undergoing chemotherapy treatment for his cancer.

The civil rights leader once marched alongside Rev. Dr. Martin Luther King, Jr. to fight for the freedom of Black people to vote in U.S. elections.

But on Sunday, Lewis announced he is in the biggest fight of his life.

"I have been in some kind of fight - for freedom, equality, basic human rights - for nearly my entire life," he said.

"I have never faced a fight quite like the one I have now."

Lewis added: "I have a fighting chance."

Pancreatic cancer is one of the few cancers that can go undetected until it is too far advanced to treat.