Protesters and security forces gather. They collide in a cloud of tear gas and a shower of rocks and bottles.
In most cases — when the battles are big and the stakes are high — journalists from around the world are there. But in the possibly history-shaping struggles now unfolding in Iran, the international media has been blocked from its normal front-line role and is quickly making adjustments to counter an official ban on firsthand reporting.
Instead of the main dispatches coming from the scenes, the equation has been greatly reversed. Many major news outlets now rely on phone calls, e-mails and Web chats — and other methods — to contact Iranian protesters and officials for information that bolsters the reports from colleagues in Tehran, who must remain in their offices.
The media clampdown also has been a test on other fronts: challenging the ability of authorities to control information in the Internet age and requiring editors and journalists to quickly decide what to pursue from the avalanche of rumors, tips and observations on social networking sites.
Some news organizations have added Farsi-speaking staff members to their usual coverage teams and stepped up attention to Web sites such as Twitter for comments and images that — if deemed credible — offer a wider view on the unfolding events.
Thomas Warhover, an associate professor at the Missouri School of Journalism, calls the social networks a "counterpart" to traditional reporting rather than a competitor.
"It's democratic impulses," he said. "People are going to find a way to be heard — new and exciting ways. That civil function is pretty incredible."
Tightening the squeeze on the Web
An international media corps remains in Tehran — mostly Iranians who work as reporters, photographers and camera operators for international or non-Iranians news organizations. But they are now being restricted to their offices, allowed only to conduct phone interviews or cite official sources such as state broadcasters.
Iranian authorities, meanwhile, have tightened their squeeze on the Web.
Authorities have blocked Web sites such Facebook, Twitter and many sites linked to opposition leader Mir Hossein Mousavi or his backers. Text messaging has been blacked out since last week, and cell phone service in Tehran is frequently down.
The Paris-based media watchdog group Reporters Without Borders said Sunday that authorities have arrested 23 Iranian journalists and bloggers since post-election protests began a week ago. It claims reporters are a "priority target" for Iran's leadership.
Among those arrested was the head of the Association of Iranian Journalists, the group said.
"It's becoming more and more problematic for journalists," said researcher Benoit Hervieu.
The restrictions on foreign media were imposed after one of the most stunning images of the showdown: hundreds of thousands of marchers pouring through Tehran last Monday to denounce alleged vote rigging in the June 12 elections and to cheer on Mousavi, who his supporters claim was the rightful winner over hardline President Mahmoud Ahmadinejad. At least seven protesters were killed in gunfire from a militia compound.
The bloodshed was covered by the world's media. One photo showed the body of one victim sprawled on the ground with blood spilling from a head wound.
Information difficult to verify
But the bar on eyewitness reporting makes it difficult to confirm reports of casualties.
Two separate videos posted on YouTube and Facebook following street battles Saturday in Tehran showed a young woman with blood pouring from her nose and mouth as people — shouting in Farsi — frantically tried to help her. The YouTube video described the location in central Tehran and said the woman, identified on the video as "Neda," had been fatally shot.
The images began to appear on media around the world, including at protests by Iranian-Americans in Los Angeles. The AP noted the existence of the videos but could not independently verify the content, its location or the date it was shot.
The AP conducted phone interviews and exchanged e-mails with protesters who witnessed Saturday's clashes with police and militia, but none of those interviewed had witnessed the scene shown on the Web sites.
"Getting out the accurate verified story is the goal," said John Daniszewski, AP senior managing editor. "The restrictions now imposed on reporters in the country make it more difficult but we are succeeding nevertheless. We rely on correspondents in Iran and those outside the country to sift fact from rumor for the most reliable dispatches possible."
Reports from 'citizen journalists
At CNN, more than 2,000 reports from "citizen journalists" related to Iran have been received since the day after the election, and more than 80 "fully verified" videos and photos have been aired, spokesman Nigel Pritchard said.
CNN also has reported on content carried by Twitter and other social networking sites, but "always placing it in context for viewers," he said.
"It is important that the audience has a clear understanding of not only that (vetting) process, but also the fact that in some cases we are not able to fully verify content from those third-party sites," Pritchard said. "Especially in a media situation like we have in Iran, it is vital that all elements of our reporting are placed in full context."
The AP monitors Twitter and other sites and has reported some posted comments on known events. But a campaign was initiated by anti-government campaigners for Twitter users outside Iran to reset their location as the Tehran area — knowing that it would increase their global exposure.
"That's great for activists, but it's terrible for journalists," said Sree Sreenivasan, dean of student affairs and a professor at Columbia Journalism School in New York. "You've been following these people who you thought were in Iran and they're not."
Last week, the British Broadcasting Corp. said it was using two extra satellites to broadcast its Farsi-language service to try to bypass jamming by Iranian authorities. The Voice of America also has added new satellite paths to counter Iranian blocks.
BBC correspondent ordered to leave
On Sunday, the BCC said its Tehran correspondent, Jon Leyne, has been ordered to leave the country. The Fars news agency said Iranian officials have accused Leyne of "dispatching fabricated news and reports, ignoring neutrality in news, supporting rioters and trampling the Iranian nation's rights."
In Dubai, United Arab Emirates, the news director for Al-Arabiya television, Nakhle Elhage, said Iranian authorities have suspended the network until further notice.
Newsweek spokeswoman Katherine Barna said that the magazine's resident correspondent in Iran, Maziar Bahari, was detained without charge by Iranian authorities on Sunday. There was no contact with Bahari, a Canadian citizen, since his detention.
Newsweek called the detention "unwarranted and unacceptable" and demanded Bahari's release.
The Reporters Without Borders researcher Hervieu said blogs, Twitter, YouTube and other Internet methods are increasingly the only way for Iranians to reach the outside world. But the use of anonymity by blog posters trying to avoid repercussions makes information difficult to verify.
Many of those posting "are both spectators and activists," blurring lines of impartiality, he said.