Shortly before 10 this morning, Amy Trachtman heard what seemed like a military jet zoom past her apartment building in Jersey City, N.J. Her first instinct? Tweet about it.

“just had a mild heart attack from a jet plane grazing the apartment…” Trachtman wrote at 9:59 a.m., becoming — as far as I can tell — the first person to publicly report on the planes that briefly terrified the New York metropolitan area today.

“I happened to just be sitting in my apartment on the computer, checking emails and whatnot and trying to read Twitter updates,” Trachtman told me in an interview. “I guess that’s why I was so fast.”

A few minutes earlier, someone in the circulation department of the Staten Island Advance came running down to the newsroom to report that her third-floor windows were rattling because a plane was flying near the building. Curious reporters ran outside, a photographer was dispatched to the roof, and someone stayed behind to call the Federal Aviation Administration.

“By then, we were already getting tons of phone calls from readers asking what was going on,” said Stephanie Slepian, an Advance reporter.

Trachtman was still unnerved by the flyby, but she continued her morning routine, which at that point, meant walking the dog. Out on the street, she noticed — and tweeted from her BlackBerry — that the building next door was evacuating. She spoke to an hysterical woman who was certain New York was under attack.

Slightly more alarmed, Trachtman turned to other news sources: “I called my girlfriend who works in Manhattan and was like, ‘Could you look online and see if there’s anything crazy happening?'” The woman first checked the website of local radio station 1010 WINS, which had no reference to any planes. Then she checked JC List, a message board populated by Jersey City residents, where a thread had begun at 10:06 a.m. with this question: “Why is there a new flight path today — low commercial planes heading towards Newark Airport EWR — pretty loud at 10am.”

By the time Trachtman’s friend checked the message board, it also had an answer, posted at 10:12 a.m. by jc_insomniac, whose neighbor had called 911 and was told not to worry, “the military is running tests.”

Over on Staten Island, Glenn Nyback, a web reporter and producer at the Advance, had already posted, at 10:03 a.m., the first mainstream news report about the planes: “FAA says low-flying plane over Staten Island is ‘pre-planned’ flight to take photos.”

This was about the time that the stock market started to dip — that’s the Dow Jones Industrial Average pictured at right, shortly after 10 a.m. — and larger news outlets in New York caught onto the story. (They were, of course, disadvantaged by the flight path.) At 10:23 a.m, Patrick LaForge, editor of The New York Times’ City Room blog and a prolific microblogger, wrote on Twitter, “We’re hearing reports of low-flying planes over lower Hudson, visible from Staten Island, Hoboken. See anything?”

The Wall Street Journal, which won a Pulitzer for its breaking-news coverage of 9/11 but isn’t particularly known for speed, beat the Times with a blog post at 10:23 a.m. entitled, “Readers: Did You See the Low-Flying Jet Over Lower Manhattan?” (Interestingly, it appeared on their business travel blog.)

City Room posted at 10:36 a.m. Both have continued to update with further information and reader photographs and video. (Are the Journal’s photos better because its readership is heavily concentrated in Lower Manhattan?)

Anyway, I don’t mean to suggest there’s any grand lesson here about reporting on the Internet. Yes, the news broke on Twitter, but the first solid reporting emerged from a newspaper — just four minutes after Trachtman’s tweet. And yet, you can’t dismiss the significance of that Jersey City message board, where calling 911 was itself a form of reporting. Plus, Slepian, the Advocate reporter, told me that they first learned one of the planes was Air Force One from readers who called into the newsroom.

I like the term “news ecosystem,” and it’s certainly an apt way to describe the various threads of reporting that occurred today. Trachtman was a citizen journalist, sure, but so was LaForge when he asked, “See anything?” And so was Trachtman’s friend when she scanned her favorite news sources and broadcast, over the phone, that there was no reason to worry.

By the way, all of this occurred in the short time between when I left my apartment in Boston and arrived at work in Cambridge this morning. That is so amazing.