(Update: A suspect has been arrested. Also, authorities now say suspects were not involved with 7-Eleven robbery.)
After days of filling the airwaves with speculation and false information, news outlets were confronted with a flood of real news early Friday: One suspect in the Boston bombings is dead and another is on the run after a night of chaos. Several news outlets said the brothers had ethnic roots in Chechnya, and a man who said he was their uncle said they were from Kyrgyzstan and had been in the U.S. for years.
News came fast and furious: At 11 a.m. ET, MSNBC said police movements in Watertown, Mass., where authorities were seeking the second suspect, resembled those that might surround a "negotiated surrender." Officers on the scene had their guns drawn.
CNN began using a five-second delay, because, the network explained, it didn't know what might happen next.
The developments came two days after a messy news day in which several outlets reported an arrest in the case, then backtracked as officials denied it. On Friday, there was more confusion, especially about the national origins of the suspects. It was at issue because of whatever clues their roots might provide about their possible motives.
CNN's Jim Walsh and Erin Burnett stressed that the suspects' Chechen roots did not mean they had anything to do with Chechen separatists who have carried out past attacks in Russia. "It could just be two men inspired by something completely domestic," said Burnett.
Overnight, the suspects shot an MIT police officer to death, committed a carjacking and threw explosives at officers chasing then, authorities said. A transit officer was also "seriously wounded and is in surgery," Massachusetts Gov. Deval Patrick said.
A huge police presence assembled in quiet, suburban Watertown, where police told residents overnight to stay indoors. By morning, officials extended that to several surrounding communities, and then the entire city of Boston. Public transporation was shut down, as were most businesses in the area.
"We're asking people to shelter in place -- in other words to stay indoors and not to open the door for anybody other than a properly identified police officer," Patrick said. He said that extended to "all of Boston -- all of Boston."
News outlets approached the story with varying levels of caution. Though the AP identified the surviving brother as Dzhokhar A. Tsarnaev, 19, of Cambridge, Mass., CNN initally gave biographical details of the suspect without naming him. Eventually it began using his name.
The AP said the dead suspect's name was Tamerlan Tsarnaev, 26. A law enforcement source told the Boston Globe that an explosive trigger was found on his body at the morgue.
CNN, Fox News and other outlets said the older brother had posted online, "I don't have a single American friend. I don't understand them."
The brothers' precise national origins were in question for much of the morning, until around 9:15 a.m., when Ruslan Tsarni, a man who said he was the suspects' uncle, told Boston CBS affiliate WBZ that the men were from Kyrgyzstan and had come to the U.S. seven or eight years ago. He also said the older brother called him Thursday and said, "Forgive me."
The Kyrgyz state news agency also said Dzhokhar Tsarnaev was a native of Kyrgyzstan, the Globe reported.
Earlier, CNN had said the suspects fled Chechnya and moved to Kazakhstan before coming to the U.S. Before that, NBC's Pete Williams said they were "legal permanent residents... in this country legally, at least a year. They appear to be from Turkey, possibly Chechens from Turkey."
Fox News' Gretchen Carlson, meanwhile, fretted about whether the suspects "received scholarships and took those away from other people in America who could have been educated and not become terrorists."
Fox News also said Dzhokhar A. Tsarnaev identified himself as a Muslim on his Facebook page. Fox's Jennifer Griffin also said his Facebook page included posts "expressing hatred toward Russia. There also is some Nazi propaganda."
Fox said a "law enforcement" source believed the page did belong to the suspect.
The biggest area of speculation was whether the brothers worked alone.
Former FBI Assistant Director Tom Fuentes told CNN the brothers did not appear to be working for a foreign group. He said accounts that they robbed a 7-Eleven seemed to suggest they had to "fundraise" because "they weren't sent here, funded, trained, ready to go directly from overseas." (Authorities said after his comments that the brothers had not actually robbed a 7-Eleven, as was initially reported.)
"From what I see, they probably weren't dispatched here," he said. "They've been in the U.S. a long time. So it doesn't appear that somebody overseas trained them and sent them on a mission. It seems that they were here, they were trying to assimilate into U.S. society and that didn't quite take. The other thing we don't know is the younger brother may have just come under the control of the older brother."
But on Fox News, former U.S. Ambassador to the United Nations John Bolton suggested the brothers were part of a "sleeper cell."
"If they've been in the country for several years I hate to put it this way but it's good terrorist tradecraft," Bolton said. "They've completely scoped out the Boston area and they took a lot of preparation to do what they've done and that's why I think we need to be concerned that there may be others who have come to this country as students or under visas of one kind or another who are simply waiting for the right moment. ... These people are direction from others overseas and I think it shows their communication security was good. We had no advance warning of it."