[Beowulf9]

Does seem coincidental.

I have never even heard of a 9 alarm fire.

[Protect the Bill of Rights]

Now a 10 Alarm fire.

[Maceman]

I have never even heard of a 9 alarm fire.

Apparently it's now a 10-alarm fire, according to local TV news.

[freeandfreezing]

I have never even heard of a 9 alarm fire.

The Boston area has had some huge fires in the past, including one which destroyed a major portion of the city of Chelsea, and another one which destroyed a collection of old mill buildings in Lynn. At that time systems were set up to ensure that firefighters from all over the area were organized to help out in the event of a large fire.

[TomGuy]

The meaning of 'alarms' varies with different fire departments.

According to Boston Fire Department Facebook:

 9th Alarm:

All of the 1st - 8th Alarm assignment and:

2 Engine Companies

 

(Total Apparatus on Scene)

21 Engine Companies

7 Ladder Companies

1 Tower-ladder Company

1 Heavy Rescue Company

6 Fire Chief ( 1 Deputy / 5 District)

1 Special Unit

1 Rehabilitation Unit

1 Air Supply Unit

More Info at Source: Boston Fire Department Facebook link

They list no info for a 10-alarm fire. It may be all of the above units plus 2 more Engine Companies.