USA Today: One dead after shots fired at Iran protest rally

Update at 2:56 p.m. ET: Mir Hossein Mousavi, the main opposition candidate in last week's presidential election, says on his website that he is not very optimistic about the outcome of his appeal to have the vote overturned, Reuters reports.
Update at 1:31 p.m. ET: State Department spokesman Ian Kelly says the U.S. is "deeply troubled" by reports of violence and arrests in Iran, the Associated Press reports.
Kelly also tells reporters that the United States is concerned about the allegations of ballot fraud in the presidential election last week.
Update at 1:30 p.m. ET: Iranian state television is also reporting that shots were fired during the protest rally, Reuters reports.
"There has been sporadic shooting out there ... I can see people running here," a reporter of Iran’s English-language Press TV said, according to Reuters.
Earleir posting: Reuters news agency is quoting a witness at a huge rally in Tehran as saying one person was killed and many wounded when "armed men" fired on a hundreds of thousands of Iranians who defied authorities to protest the disputed re-election of President Mahmoud Ahmadinejad.
The witness, an Iranian photographer, said people in the crowd had attacked a building housing members of a religious militia, who then opened fire, the news agency says.
The Associated Press says its photographer saw pro-government militia fire at opposition protesters, killing at least one person.
The BBC says its correspondent in the Iranian capital, Jon Leyne, is calling the rally the biggest demonstration in the Islamic republic's 30-year history and describes it as a "political earthquake."