We've been following with a mix of fascination, sadness and fear the tragic killing of four police officers near Tacoma, the subsequent siege of the alleged shooter at a home in Seattle's Leschi neighborhood and now the alarming news that the suspect may be roaming the University District or Beacon Hill.

And we've been tracking all of this primarily on Twitter, where the events have played out almost in real time under the hash tag #washooting. Could this be a watershed moment for the use of Twitter and other social media tools in Seattle journalism? It appears so.

A wide variety of sources -- from traditional journalists to government agencies to ordinary Seattle residents -- have been combining to create one unified stream of news. And one could argue that it's a much more powerful and informative stream than any single news organization could muster. [Post updated with The Seattle Times crediting Twitter for its record traffic on Monday of 3.3 million page views.]

Last night, as the alleged shooter barricaded himself inside a home in Seattle's Leschi neighborhood, we Seattle Internet entrepreneur Buzz Bruggeman -- who lives a few blocks away -- offered a constant stream of updates about the police activity in the neighborhood.

"I feel a bit like Edward R. Murrow in London, can't see much, street blocked, flares are now burned out, unmarked cars here, copter too," wrote Bruggeman in one tweet.

Bruggeman

Bruggeman, CEO of technology company ActiveWords, was one of hundreds of "citizen journalists" who added context and insight to the events as they unfolded, creating a powerful source of information that we've not quite seen before around a news event of this size in Washington state.

In an email this morning, Bruggeman explained that he didn't see himself doing anything "earthshaking or watershed, just paying attention, and trying to add to the conversation/story." He first noticed the police descend on his neighborhood around 9:50 last night. After checking the news and Twitter for information about what was happening around him, he realized there was none, so he figured he should start posting updates himself.

He ended up picking up about 50 new followers on Twitter, some local, others international. The "real news guys" didn't start showing up in the neighborhood with their cameras until about an hour after the incident started.

"As I look at what I have written, what I guess is striking is how timely my tweets were, but yet no curation, editing or real focal point that people could have gone to. The people who followed me either on Twitter or Facebook got a real time sense of what I was seeing," he says. At the same time, it was a learning experience for him: "On reflection I am sorry that I didn’t both take some pictures and post them, and also walk down and talk to the cops on the fringe to do a better job of reporting something beyond what I was seeing from my windows and deck."

As Bruggeman and others were offering details about what was happening around them, the Central District News also was filing Twitter dispatches from the scene, as were reporters from SeattlePI.com and The Seattle Times.

It was on Twitter this morning that we first learned through a "citizen journalist" that officials at the University of Washington had sent a text message warning students and staff that the alleged shooter might have been in the University District. It was also on Twitter that we learned (via a KING5 tweet) that the suspect had previously been shot, and that the suspect was no longer holed up in the Leschi home.

Through it all, there have been thousands of Tweets from citizens expressing outrage, grief and sadness. Their stories have helped tell the story in a new, more personal way.

Of course, as with any news medium, you have to consider the source. And there's certainly been some good information mixed in with the bad. We've also seen this play out on Twitter over the past few days following Tiger Woods' car accident, where rampant speculation has made it difficult to discern the real news.

That's where traditional, trusted news sources need to stand out by doing the jobs of professional journalists -- sorting out fact from fiction while reporting from the scene.

But overall, particularly in the case of the police shootings, the most in-depth and timely information has come not from one source but from a variety -- all of them brought together in a compelling demonstration of the potential of social media.

UPDATE: In a story in Editor & Publisher, editors at The Seattle Times credit Twitter with helping to drive record traffic at the newspaper's Web site on Monday. The site attracted 3.3 million page views, with Tweets from reporters the third most read item on the site. The newspaper also experimented with Google Wave, with 500 participants at one time.

[Post updated at 10:30 a.m. with additional details from Bruggeman.]