GEOFF BENNETT: Shifting now to the day's other major story, federal investigators are trying to figure out what led to a collision between a commercial airliner and a fire truck on the runway at a New York airport last night.

The two pilots of the plane are dead and dozens more are injured.

The officials say LaGuardia Airport will operate at a reduced capacity for some time.

As Stephanie Sy reports, it comes at a moment when the nation's air system is under considerable stress.

STEPHANIE SY: A jet barrels down a rainy runway and crashes into a crossing truck.

The late-night collision wrecked the cockpit and jolted passengers.

MAN: We were -- I was, honestly, sleeping and landing, and, all of a sudden, boom, woke up in shock.

Just didn't know what to do.

STEPHANIE SY: Minutes before midnight, a plane carrying 72 passengers and four crew members collided with the fire truck on the tarmac of one of New York's busiest airports.

The pilot and co-pilot were killed.

And dozens of passengers, as well as Port Authority officers in the fire truck, suffered injuries.

WOMAN: One of our friends was several rows back from us.

And we walked past him on the way out because he was trying to find his glasses.

And his nose was totally broken, bleeding on his face.

Like, a lot of people smacked their head against the seat in front of them.

STEPHANIE SY: The impact was enough to crush the Air Canada jet's nose, tilting the plane on its tail.

The fire truck was mangled beyond recognition.

Minutes before the collision, an air traffic controller had cleared the truck to cross the runway.

An audio recording reveals the moment a controller tries to prevent the crash.

MAN: Stop, truck one.

Stop.

Stop, truck one.

Stop.

STEPHANIE SY: He's then heard frantically redirecting other flights about to land to different runways.

And then, later, this conversation is picked up.

MAN: I tried to reach out to my staff, and we were dealing with an emergency earlier.

I messed up.

STEPHANIE SY: He says: "I messed up."

Whether he did or not, investigators with the National Transportation Safety Board are now on site at LaGuardia to get to the bottom of what happened.

The airport was closed for most of the day.

KATHRYN GARCIA, Executive Director, Port Authority of New York: We will follow their lead on what their investigation requires, and they will have the time they need to make that determination.

STEPHANIE SY: The latest runway incursion is raising alarm among aviation analysts.

MILES O'BRIEN: The air traffic control system is kind of a shadow of what it should be.

STEPHANIE SY: Miles O'Brien is "News Hour"'s aviation correspondent.

MILES O'BRIEN: It's way understaffed, and, as a result, the controllers are working mandatory overtime as a matter of routine.

There's a lot of stress and fatigue that is built into this system and, frankly, a lot of heroic efforts on the part of the air traffic controllers to make the system safe.

But we shouldn't be relying on heroic efforts to make a system safe.

STEPHANIE SY: He also says LaGuardia's runways are designed to prevent this kind of crash.

MILES O'BRIEN: So there are 20 airports, give or take, in the U.S.

that have this technology called runway status lights.

It basically detects the movement of an aircraft takeoff or landing when the runway should be cleared except for that aircraft.

And when it detects the presence of the aircraft, if it's working properly, it should have a red light on the taxiway leading to the runway.

This system is designed to prevent exactly what we just saw.

And if it failed, it's something that needs to be considered, along with the overall problems with air traffic control.

STEPHANIE SY: The latest deadly incident occurs amid turmoil at many of the nation's airports.

A partial government shutdown due to political disputes over immigration enforcement tactics has led to gridlock for travelers.

The shortage of TSA workers, combined with heavy spring break traffic, has meant long lines at airports.

Travelers leaving Atlanta today were advised to arrive four hours early to make their flights.

ANDRES CAMPOS, Air Traveler: Oh, my God, this is insane.

I mean, I have never experienced anything like this.

It's crazy.

It's insane.

I mean, I have never seen an airport like this.

STEPHANIE SY: In a controversial step, President Trump has directed DHS to deploy federal Immigration and Customs Enforcement agents at TSA checkpoints.

The ICE officers are fanning out across more than a dozen airports today.

DONALD TRUMP, President of the United States: I want to thank ICE, because they stepped in so strongly.

They will do great.

And if that's not enough, I will bring in the National Guard.

STEPHANIE SY: Meanwhile, the political stalemate continues.

DONALD TRUMP: And I told the people, don't settle.

Don't settle, because we have something bigger.

STEPHANIE SY: The lack of a political settlement means air travel may also remain unsettled for millions of travelers.

For the "PBS News Hour," I'm Stephanie Sy.