Tragedy struck on a United flight from Houston to New York City, when a dog in a TSA-compliant pet carrier died after a flight attendant forced its owner to store the animal and its carrier in an overhead bin for the duration of the four-hour Monday flight.

First reported by travel blogger The Points Guy, United has since claimed full responsibility for the “tragic accident.”

According to passenger Maggie Gremminger, she and others heard the black French bulldog barking initially during the flight, and were horrified to learn the animal had passed away later in the trip, she told People.

“A stranger offered to hold her newborn while she sat on the floor, there in the airplane aisle. She was holding her dog and rocking back and forth. Her daughter was also crying,” Gremminger told the publication of the scene following the discovery.

Gremminger told People once the dog was found dead, the flight attendant became “frazzled” and insisted she did not know there was a live animal in the carrier.

“I want to help this woman and her daughter. They lost their dog because of an @united flight attendant. My heart is broken,” Gremminger wrote on Twitter, sharing a photo of the family who allegedly lost their dog.

For their part, United’s pet policy reads as follows:

I want to help this woman and her daughter. They lost their dog because of an @united flight attendant. My heart is broken.

11:15 PM – Mar 12, 2018
320 people are talking about this
Twitter Ads info and privacy
“A pet traveling in cabin must be carried in an approved hard-sided or soft-sided kennel. The kennel must fit completely under the seat in front of the customer and remain there at all times.”

United Airlines spokesperson Maggie Schmerin returned Fox News’ request for comment with the following statement:

“This was a tragic accident that should never have occurred, as pets should never be placed in the overhead bin. We assume full responsibility for this tragedy and express our deepest condolences to the family and are committed to supporting them,” she said.

“We are thoroughly investigating what occurred to prevent this from ever happening again,” Schmerin added.

The cause of death is not yet known, but, while the overhead compartments are not air-tight, lack of oxygen may have been a factor.

The heartbreaking news comes weeks after United and Delta made headlines for tightening rules for flying with animals amid emotional support and service animal controversy.

see pics