TUCSON, Ariz. (AP) — U.S. Rep. Raúl Grijalva announced Tuesday that he has been diagnosed with cancer, but he said he is continuing to work as he undergoes treatment.

“A few weeks ago, I sought medical treatment for a persistent cough which was initially diagnosed as pneumonia. After further testing and imaging, my physician discovered that I have cancer,” the 76-year-old Democrat, who is the dean of Arizona’s congressional delegation, said in a statement.

“This diagnosis has been difficult to process, but I am confident in the vigorous course of treatment that my medical team has developed, and I’ve begun my journey to fight this cancer,” Grijalva added.

It is unclear what type of cancer Grijalva has. The congressman’s office said no other information was being released at this time.

“I am working hard to get healthy and return to business as usual as soon as I am able,” said Grijalva, who was first elected to the U.S. House in 2002.