When two bombs exploded at the finish line of the Boston Marathon, killing three and injuring more than 100, late-night TV show hosts once again struggled to open their comedy programs hours later.

With Boston semi-native Jay Leno having the night off, you’d have thought it would’ve been Conan O’Brien’s night, what with him being a local boy too.

Instead, surprisingly, he decided to make perfunctory visits to those stations of the cross which must be visited by late-night comedy hosts on days of great tragedy:

1) Opening Line/Whiplash

2) Personal Connection to Tragedy

3) Self-Deprecating Joke Seguing Back to Regularly Scheduled Funny Business/Celebrity Project Plugging.

It went like this:

* Opening Whiplash: “We have a great show for you tonight — but first, I have to mention what an upsetting and sad day it’s been.”

* Personal Connection: “Boston is my hometown, it’s where I grew up and it’s where my family lives...So I just wanted to take a moment to say that, like everyone here, my thoughts and prayers are with the people of Boston, and everyone who has been affected by this senseless act.

* Self-Deprecating Segue: “That said, it is our job to do a show. We’re going to try and entertain you the best we can — which, given our track record, gives you people at 20 percent chance of having a good time tonight.”

ABC’s Jimmy Kimmel appeared not to have any personal connection to Boston:

“It was a terrible day,” Kimmel opened.

“Very bad things happened today for no good reason, and our thoughts are with the people of Boston, and everyone who is suffering as a result of the bombings at the marathon. It’s a disgusting thing. I don’t understand it. But my job is to make you laugh and so I will try to do that. And I will probably fail. I’m failing already.”

Jimmy Fallon, current “Late Night” host, who’d just been crowned heir to the “Tonight Show” — the biggest franchise in late night TV — was, like Leno, scheduled to have the night off. This was a lucky break for Fallon because, while possessing many talents, gravitas is not among them.

David Letterman, who defined gravitas when he brought his CBS late night show back to the air after the Sept. 11, 2001 attacks, also had the night off.

That left CBS’s Craig Ferguson once again defining the moment Monday night — and Reporters Who Cover Television harkening back to July of 2012 when he’d similarly tossed out the opening monologue he’d pre-taped for his show that aired in the wake of the movie-theater shooting in Aurora, Colo., and delivered a thoughtful, extemporaneous opening to an empty studio.

Back then he explained to viewers that the rest of the show would air as taped, because to pull it entirely would have been unfair to the guests, while observing every time something like the Aurora shooting occurs, “we are all diminished.”

Ferguson has an enormous advantage over his day-part colleagues, in that he begins every show with “It’s a great day for America,” which makes for high drama on nights when he decides it’s not.

“Is anyone else sick of this [expletive]?” Ferguson ranted at the top of Monday’s show.

“I seem to have to say that too often — I have to NOT say ‘It’s a great day for America’ because of some random act of madness or terrorism.”

People say to me, ‘Craig, your job is to make people laugh at the end of the day.’ And I think yes, that’s true — but I’ve never professed to be any damn good at that,” he continued, coaxing his studio audience with permission to laugh.

“And, the thing is, people want their mind taken off it. And I think, well ok, if you want your mind taken off it, watch a cartoon or a video or something. I understand it, it’s perfectly acceptable. I don’t think it’s a terrible thing to not want to think about it. But I can’t not think about it…I can’t pretend it’s not there — I’m not a valuable, quality entertainer.”

“So, we’ll have our guests out tonight and I’ll ask them about their lives, but I don’t know how it’s going to be,” Ferguson continued, adding, “Luckily, we have a couple of guys tonight...They’re intelligent, experienced, clever men.”

Those intelligent, experience clever men were the previously announced Rob Lowe — and former CNN star Larry King, who’d been booked about 90 minutes before Ferguson’s show taped.

King replaced Brad Goreski — because somehow chatting with the former style director/assistant to celebrity stylist Rachel Zoe about his Bravo series “It’s a Brad, Brad World” didn’t seem right on such a night.