(CNN) — Sylvester Turner, a Democratic congressman and former mayor of Houston, has died, according to Houston Mayor John Whitmire. He was 70.

“A remarkable public servant who impacted millions of people. He rose from poverty but never forgot where he came from. It is a terrible loss for the city and a personal loss for me. I ask Houstonians to celebrate his life,” Whitmire said in a statement posted by the City of Houston.

House Democratic leadership informed members of Turner’s death during a meeting Wednesday morning, according to a source in the room.

Later in the day, House Minority Leader Hakeem Jeffries and Democratic colleagues held a moment of silence at an afternoon event in honor of Turner, calling his passing tragic and unexpected. The Democratic leader remembered Turner as a “powerful, profound principled public servant.”

Turner was sworn into Congress in January after serving eight years as the mayor of Texas’ biggest city. Before that, he also spent 27 years in the Texas House where he was a powerhouse on the state’s appropriations panel.

Turner came out of retirement to succeed the late Rep. Sheila Jackson Lee, who was her own force in Texas politics during her two decades in the US House.

Turner was the preferred pick by Jackson Lee’s children in the competitive primary to replace her after her death in July 2024. He vowed to, like Jackson Lee, devote his time to securing federal resources for the sprawling district.

The cause of Turner’s death was not immediately clear. The 70-year-old said in 2022 that he had been treated for bone cancer but declared himself “cancer free” in an interview with the Texas Tribune later that year.

His death came as a shock for his fellow congressional Democrats, who had sat with him at the president’s joint address Tuesday evening. He attended the speech with his guest, a Houston resident and mother whose 2-year-old daughter has a rare genetic condition and relies on Medicaid to survive.

In recent months, Turner had been outspoken — and in his words, “hopeful” — about how Democrats can rebound from the GOP’s electoral win in November.

“I’m optimistic simply because I know what we are made of,” Turner told a crowd at the Houston Black American Democrats last month. “The only way that we lose is that we fail to use what we have.”

“I’m hopeful. I did not come with a head bowed. I know the president is in office. A lot of things he has done. But I’m optimistic. I’m positive. I don’t have a hard time going to bed at night.”

This story has been updated with additional details.

CNN’s Veronica Stracqualursi contributed to this report.