Reports of shots fired, explosives, grenades in Watertown, Mass. after MIT shooting/carjacking. Listen live: http://t.co/b4cvj6FOYM — Tom Cleary (@tomwcleary) April 19, 2013

Whoa. Twitchy told you about the fatal shooting of a police officer at MIT earlier tonight. According to Twitter users in the Boston area, there’s a frenzy of law enforcement activity after a carjacking that may be related to the campus shooting.

770 am NYC giving play by play with MIT, Mercedes carjacking, and now rumored GRENADES? Holy crap. — Jon Harder (@TheJonHarder) April 19, 2013

Report of Shots Fired and possible explosives & Grenades. Watertown, MA – LOUD EXPLOSION – Black Mercedes Carjacking — Domani Capital (@AdaptToReality) April 19, 2013

Hmm. We’ll see:

I have a feeling the MIT shooting/carjacking/grenade explosions happening in and around Boston is connected to Marathon bombing. We'll see. — Bryan Padgett (@bpadge) April 19, 2013

Writer/MIT prof Seth Mnookin tweeted from the scene on campus as the latest chaos ensued:

Boston PD scanner talking stolen cars, seem in ref to MIT shooting – talk about Mass Ave & Albany (Cambridge) less than mile from scene. — Seth Mnookin (@sethmnookin) April 19, 2013

"We have a bag of articles, I have a possible witness." – Boston PD scanner. "Just outside of the incident." — Seth Mnookin (@sethmnookin) April 19, 2013

More talk of vehicles, mile down from Kendall Sq., on Boston scanner. Can't tell if in ref to MIT shooting; regardless: STAY AWAY FROM AREA — Seth Mnookin (@sethmnookin) April 19, 2013

K-9 units at scene at MIT. Mass State Police holding down center of scene. — Seth Mnookin (@sethmnookin) April 19, 2013

Series of fire trucks, ambulances, detectives just tore down Main St through press area outside of MIT shooting. — Seth Mnookin (@sethmnookin) April 19, 2013

MIT alert at 12:01: "Police are sweeping the campus at this time, please continue to stay indoors and remain inside until further notice." — Seth Mnookin (@sethmnookin) April 19, 2013

I'm at scene. “@spcraft: @sethmnookin Did you get that from the scanner? Can't find anything definitive here” — Seth Mnookin (@sethmnookin) April 19, 2013

Six state police cars just left scene towards Central Square. In a hurry. — Seth Mnookin (@sethmnookin) April 19, 2013

Memorial Drive and River St – new crime scene, report of carjacking; 2 armed men. Carjacking victim left at Sunoco or Mobil station. — Seth Mnookin (@sethmnookin) April 19, 2013

Carjacked vehicle lojacked to Watertown. State police screaming towards Watertown. — Seth Mnookin (@sethmnookin) April 19, 2013

Shots fired at officers in Watertown. — Seth Mnookin (@sethmnookin) April 19, 2013

Reports of massive explosions and grenades. Can smell smoke in Watertown near Arsenal Mall. — Seth Mnookin (@sethmnookin) April 19, 2013

Suspects have "stolen SUV from state police." – Boston pd scanner. — Seth Mnookin (@sethmnookin) April 19, 2013

The suspects reportedly have “long guns:”

Explosives at the scene. Officer down. Suspects with long guns. — Seth Mnookin (@sethmnookin) April 19, 2013

"All units retreat. There are explosives on scene." Boston PD officer down; Watertown ambulance transporting. — Seth Mnookin (@sethmnookin) April 19, 2013

"Plain clothes officers on scene – go to road, maintain perimeter, do not go through back yards." — Seth Mnookin (@sethmnookin) April 19, 2013

At scene in Watertown: "Identify yourself." "Press." "Stay back." — Seth Mnookin (@sethmnookin) April 19, 2013

Photos:

Mt auburn rd in Watertown. Police moving people back. #bostonshootout pic.twitter.com/CESNCUQmac — Jay Newton-Small (@JNSmall) April 19, 2013

Twitchy will continue to monitor and update with breaking developments.

Live video following reports of gunfight, explosives in Watertown, Massachusetts – @WCVB http://t.co/v2OyZnzFAF — Breaking News (@BreakingNews) April 19, 2013

#wcvb reporter Todd Wallace sees police officers in heavy body armor walking Mt Auburn going in the direction of Dexter #watertown — WCVB-TV Boston (@WCVB) April 19, 2013

WCVB is reporting that Homeland Security is on the scene in Watertown. — Matt Terl (@matt_terl) April 19, 2013

Live streaming right now:

"One suspect down, one in custody." Watch: RT @cbsboston: WBZ-TV Streaming Coverage Live http://t.co/r59uECrl38 — Tim Wieland (@CBS4Tim) April 19, 2013

Insanity. 10hrs after FBI releases photos of marathon suspects, four men in Watertown, MA, firing machine guns, lobbing grenades at police. — Neal Rogers (@nealrogers) April 19, 2013

Several reports on Twitter, via police scanner, that officers have been told to power down their cell phones to avoid triggering possible IEDs.

Boston Police Scanner: Officers being repeatedly told to power down cellphones. If you live in Watertown, MA, shut your cellphone off. — Peter Stringer (@peterstringer) April 19, 2013

"All Cambridge units in Watertown immediately power down your cell phones." – police scanner — Billy Baker (@billy_baker) April 19, 2013

Two suspects now in custody?

Second suspect in custody #watertown — Adam Gaffin (@universalhub) April 19, 2013

Or is second man still out there?

Now the scanner is saying that they "may not have the second suspect." "We potentially still have a second suspect out there." #Watertown — Kris Jones (@RavenManiac) April 19, 2013

"Confusion as to 2nd suspect location: "We potentially still have a second suspect out there." #Watertown #BPD Scanner" (v @ASE) — Sara . (@Sara723) April 19, 2013

Image of suspect on ground pic.twitter.com/ZTm5WehC7L — Kathryn Swartz Rees (@kathrynswartz) April 19, 2013

More from Mnookin on scene:

"KEEP YOUR FUCKIN HANDS WHERE THEY ARE. DON'T MOVE YOUR FUCKING HANDS." At scene in Watertown (not to me; in yard around corner." — Seth Mnookin (@sethmnookin) April 19, 2013

Police putting on flak jackets. Suspect in vehicle. Getting "long rifles." — Seth Mnookin (@sethmnookin) April 19, 2013

Lots of shouting. Police are trying to remove suspect from car. — Seth Mnookin (@sethmnookin) April 19, 2013

"Get out of car. Lift up your shirt with left hand. Keep hands above your hand." — Seth Mnookin (@sethmnookin) April 19, 2013

"We have a second suspect in custody, we need an ID that it's him, we're not sure that it's him." — Seth Mnookin (@sethmnookin) April 19, 2013

Police just loaded naked man into car. — Seth Mnookin (@sethmnookin) April 19, 2013

Reporter on scene on cell phone: "can I speak to somebody who can make a decision?" — Seth Mnookin (@sethmnookin) April 19, 2013

Air support called in. Scanner traffic has explosives strapped to suspect; did not see that here. — Seth Mnookin (@sethmnookin) April 19, 2013

Actual perimeter just now set up. My car one block beyond this. pic.twitter.com/SvnvC1nbVz — Seth Mnookin (@sethmnookin) April 19, 2013

I didn't hear any gunshots at scene (Dexter St & Nichols). Lots of talk on scanner, though. — Seth Mnookin (@sethmnookin) April 19, 2013

When I got here, police were asking to use my phone to navigate neighborhood. Two mins later, told in no uncertain terms to leave area. — Seth Mnookin (@sethmnookin) April 19, 2013

Just wow:

I've listened to a lot of scanner traffic over the last twenty years. None of it comes close to what just went down in Watertown. — Blogs of War (@BlogsofWar) April 19, 2013

Now, as of 1:30am-ish Eastern activity related and a lockdown at Children’s Hospital:

Children's hospital locked down. Oh shit — Dave Willett (@youngblood905) April 19, 2013

The Children's Hospital is in lockdown now but the scanner didn't say why. #WaterTown — Kari Van Horn (@KariVanHorn) April 19, 2013

1:39am Eastern: “We do not have a second suspect in custody.”

.#Watertown Scanner: "We DO NOT have a second suspect in custody." — Mike Masco (@MikeMasco) April 19, 2013

Another person live-tweeting from scene in Watertown:

Green accord license: 116GC7 involved in shooting. Crashed cop car windows shot out. 62 laurel #mitshooting #boston pic.twitter.com/BHFvp42UkC — Andrew Kitzenberg (@AKitz) April 19, 2013

Dark video of black Benz in shoot out with Watertown on laurel st PD #mitshooting #boston #mit http://t.co/BYg7RaqDcC — Andrew Kitzenberg (@AKitz) April 19, 2013

1:45am Eastern. Police scanner traffic indicates suspect at large is “Middle Eastern” looking male, clean shaven, wearing a blue shirt with a “Christmas style” hat bearing a snowflake.

Suspect description via scanner: middle eastern male, clean shaven, with a Christmas-looking cap… — Daniel Paulson (@blowuptheocean) April 19, 2013

https://twitter.com/BlackDove3/status/325124690832134144

Mt. Auburn Hospital reportedly on Code Black:

https://twitter.com/ultragrrrl/status/325124290150297600

And more:

Suspect vehicle has multiple bullet holes in it. — Steve (@alertnewengland) April 19, 2013

Abandoned SUV at Lincoln and Spruce St., Watertown — Adam Gaffin (@universalhub) April 19, 2013

House at 39 Oak St. has ballistic evidence – inside. — Adam Gaffin (@universalhub) April 19, 2013

2:12am Eastern. A perimeter has been set up around a house on Hazel St.

Perimeter is established around the house. There is a street behind 14 Hazel that has to be covered. — Matt Miller (@nfldraftscout) April 19, 2013

Good map of the Watertown area RT @universalhub: Perimeter being set up around 14 Hazel St. Map: http://t.co/ly0wH17wki — Neville Williams (@Solar257) April 19, 2013

Colleagues reporting that Federal officials, including ATF and FBI on scene at Watertown shooting. We don't know why. — Janet Wu (@JanetWuNews) April 19, 2013

2:49am Eastern. The hunt for the fugitive suspect continues. The Boston Globe runs a front page headline declaring the Watertown suspects the same suspects identified in the Boston Marathon bombing. Scanner traffic now indicating that the suspect at large is the same Boston Marathon bombing suspect who wore a white hat in the pics released to the public.

#tgdn EXCLUSIVE NEW photo of suspect #1 released enhanced composite of #1 and # 2 pic.twitter.com/rwKIFYdwNq — Mikael (@Wolfi_Z) April 19, 2013

Scanner: "Party outstanding…suspect with white hat seen in the photos". #Boston as of 2:46 AM Watertown Control — Ryan Maue (@RyanMaue) April 19, 2013

Police Scanner: "The white male considered armed and dangerous. Possibly with explosives and assault rifle." #Watertown — Enrique Acevedo (@Enrique_Acevedo) April 19, 2013

"White male, black curly hair should be considered armed and dangerous, possibly with an assault rifle and explosives" #BostonScanner — Stephanie McMaster (@Smethanie) April 19, 2013

Updates:

Named: Suspects identified on police scanner as Mike Mulugeta, Sunil Tripathi; one ‘suspect is running’

Boston Marathon suspect Sunil Tripathi in a Che Guevara t-shirt