PITTSBURGH (REUTERS) - US prosecutors will seek the death penalty for Robert Bowers, the man accused of bursting into a Pittsburgh synagogue last year with a semi-automatic rifle and shooting 11 people to death, according to court papers filed on Monday (Aug 26).

Bowers, 46, shouted "all Jews must die" as he fired on congregants gathered for a Sabbath service at the Tree of Life synagogue on Oct 27, authorities said.

Bowers has pleaded not guilty in US District Court in Pittsburgh to a 63-count indictment.

The charges he faces include using a firearm to commit murder and obstruction of free exercise of religious belief resulting in death. Also, he targeted vulnerable people, because some of his victims were elderly, and demonstrated a lack of remorse, federal prosecutors said in court papers.

An attorney for Bowers, death penalty specialist Judith Clarke, did not immediately return a call seeking comment.

The mass shooting followed a rise in the number of hate crimes and the number of hate groups in the United States, according to separate reports from the Federal Bureau of Investigation and the Southern Poverty Law Center.