The Boston Fire Department reports a fire caused by "careless disposal of a cigarette" shortly after 7 p.m. yesterday did an estimated $50,000 in damage to the three decker at 90 Hancock St.

UPDATE: Fire officials blame "careless disposal of a cigarette" on a first-floor porch.

The Boston Fire Department reports a lit cigarette butt started a fire in the wooden beams that hold up a hollow sidewalk outside 140 Boylston St. shortly after 2 p.m.

This is a hollow sidewalk supported at points by wooden floor joists. A small hole in the sidewalk received a cigarette butt.

The joists caught fire. Firefighters used their sledge hammer to open up the sidewalk to get at the fire and extinguish it

No injuries. Some smoke in the basement. Public Works called to bring steel plate to cover hole for now.

So now we know why you can't park on a hollow sidewalk: You might fall through into a bottomless abyss.

This fall, Northeastern students, faculty and staff will have to leave the butts at home - the school tomorrow will announce plans for a smoke-free campus, both indoors and outside. In an e-mail to students today, Terry Fulmer, dean of Bouvé College of Health Sciences writes:

The Boston Fire Department has released its findings on the fire that killed BU student Binland Lee on Sunday:

The fire was started by the careless disposal of smoking material.

Specifically, it started in the area of an interior staircase that was permanently blocked off on the first floor but was an open space to those using the stairs to the second floor from the rear of the house. ...

This determination was based on physical evidence, burn patterns, interviews and other factors.

The Boston Fire Department reports the cause of the roof fire that did an estimated $1 million in damage to 182 Beacon St. in the Back Bay yesterday:

Fire Investigators have determined the cause of the roof deck fire at 182 Beacon St. to be careless disposal of a cigarette. Specifically, on the roof deck was a flower pot being used as an ashtray.

The Boston Fire Department reports inspectors have figured out the cause of a six-alarm fire on Wednesday:

Careless disposal of a cigarette on the 3rd floor rear porch of 10 Fox St. Fire then extended to 12 Fox St. & 8 Juliette St.

MBTA Transit Police report officers on routine patrol at South Station on Tuesday morning noticed a guy "standing directly beneath a posted 'No Smoking' sign smoking a cigarette," and

Expensive pack of smokes. Moreland Street photo by BFD.

The Boston Fire Department reports a fire at 114 Bayswater St. did an estimated $40,000 in damage.

Fire officials say the blaze, called in around 11:45 a.m., was confined to the top-floor porch of the house with a cannon out front. Cause: "Careless disposal of a cigarette."

No injuries were reported.