The authorities simultaneously thanked members of the news media for spreading the word that Bostonians should take shelter and remain alert — and cautioned them against repeating secondhand or thinly sourced information. The Massachusetts State Police asked local and national television networks to refrain from showing any live video of police movements, and for a time the Federal Aviation Administration restricted news helicopters from hovering above the area where one of the suspects in the bombing of the marathon Monday was believed to be hiding.

Members of the news media by and large complied. “We’ve only been showing the feeds that authorities are comfortable with,” the CNN anchor Chris Cuomo told viewers about 10:45 a.m., 12 hours after the chaotic situation started with a shooting in Cambridge, just across the Charles River from Boston.

Nevertheless, reporters were positioning themselves as closely as they could to the action in Cambridge and nearby Watertown, at times being pushed back by law enforcement officials. At one point, Kerry Sanders, a correpondent for NBC, was reporting while crouching for his own safety, in a scene evocative of wartime coverage from the Middle East.

“Officials urged us to exercise caution in showing live pictures or to describe detailed views of the movements of tactical officers, a concern which we shared,” said Antoine Sanfuentes, a senior vice president of NBC News. “We used the utmost discretion as we transmitted live pictures by putting them on a delay and avoided giving highly detailed accounts of the movements of officers.”

The CNN correspondent Deborah Feyerick, who was near Mr. Sanders, insisted that the channel’s coverage pause so that it could be put on a delay. Such delays are common when broadcasters are concerned about accidentally showing violent or graphic images.

The tension also played out on Twitter, where chatter followed the manhunt before dawn on the East Coast and into the morning. Seemingly every utterance from the local police scanners was repeated, often without any context. Twitter users urged one another not to share what they were hearing on the scanners, and by midday the audio feeds on at least two scanner Web sites were no longer working.

There was at least one case of mistaken identity. Late Thursday and early Friday, some users of Twitter, Reddit and other social Web sites homed in on the visual similarities between a Brown University student reported missing in March and one of the suspects identified by the F.B.I. For a time, the student’s name was trending nationwide on Twitter. But reporters, relying on law enforcement sources, shot down the suggestion that the student was a suspect.

The missing student’s family issued a statement later on Friday saying that the speculation had been “painful” and added, “We are grateful to all of you who have followed us on Facebook, Twitter, and Reddit — supporting us over the recent hours.”

This mistaken identification of the student came after several days of frenzied, sometimes inaccurate reporting about the bombings. On Wednesday, the F.B.I. chastised news media outlets that mistakenly reported an arrest in the case, saying it could have “unintended consequences.’’ But the complex relationship was highlighted two days later, when the authorities used the news media to help disseminate photographs of the two men it was seeking as suspects.

As the morning turned to afternoon, the nation’s major television networks continued to pre-empt all other programming for live coverage from Boston and from Watertown, the suburb where the manhunt was said to be unfolding. On several occasions, reporters and camera crews found themselves on what amounted to the police front line, able to describe and televise the action — at least until the police forced them to move farther away. Mr. Sanders of NBC crouched on the ground with his camera operator when the authorities suggested there was an imminent threat. He later said a police officer told him, “If you knew what was going on, you wouldn’t be standing here right now.”

Bill Carter and Christine Haughney contributed reporting.

Article source: http://www.nytimes.com/2013/04/20/us/media-becomes-part-of-story-in-boston-manhunt.html?partner=rss&emc=rss