BERLIN — Three men attacked a lawmaker from the far-right party Alternative for Germany, the police said Tuesday, leaving the official with serious injuries to his head and upper body.

The lawmaker, Frank Magnitz, 66, the leader of the party’s chapter in Bremen, was attacked on Monday and remained hospitalized on Tuesday, Thomas Jürgewitz, the deputy head of the Bremen chapter, said in a telephone interview. He added that Mr. Magnitz was expected to make a full recovery.

A photograph posted to Facebook by the AfD Bremen chapter showed Mr. Magnitz bloodied and bruised, with a deep gash on his forehead. The brutality of the attack and the rarity of such violence against a public official prompted widespread condemnation and calls for justice from across the country’s political spectrum.

“The brutal attack on the member of the Bundestag Frank Magnitz in Bremen is to be condemned sharply,” Steffen Seibert, a spokesman for Chancellor Angela Merkel’s government, wrote on Twitter. “Hopefully, the police will be able to catch the perpetrators quickly.”