Three hours in an overhead compartment proved too much for a 10-month-old puppy, who died on a United Airlines flight from Houston to New York Monday night.

United Continental (UAL) apologized for the dog's death in an emailed statement on Tuesday, calling it a "tragic accident that should never have occurred, as pets should never be placed in the overhead bin."

Shortly after boarding United Flight 1284 to New York's LaGuardia, a passenger was told to place the French bulldog, called "Papacito," and its carrier in the overhead, June Lara, a passenger sitting nearby reportedly said.

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The flight attendants "felt that the innocent animal was better off crammed inside the overhead container without air and water," Lara wrote on Facebook. "They INSISTED that the puppy be locked up for three hours without any kind of airflow. They assured the safety of the family's pet so wearily, the mother agreed."

The scenario violates the carrier's policy, which states in part: "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 said it would assume full responsibility for the incident and that it was investigating what happened to prevent such an incident from happening again.

"There was no sound as we landed and opened his kennel. There was no movement as his family called his name," Lara wrote. "I held her baby as the mother attempted to resuscitate their 10 month old puppy. I cried with them three minutes later as she sobbed over his lifeless body. My heart broke with theirs as I realized he was gone."

Another passenger on the flight posted a photo on Twitter of the dog's owner and children after the plane had arrived in New York. "I want to help this woman and her daughter," she wrote. "They lost their dog because of an [U]nited flight attendant. My heart is broken."

I want to help this woman and her daughter. They lost their dog because of an @united flight attendant. My heart is broken. pic.twitter.com/mjXYAhxsAq — MaggieGremminger (@MaggieGrem) March 13, 2018

The puppy's death is not the first such incident for the carrier. In 2017, United also apologized for the death of a dog that had been put in the cargo hold of a plane held for hours on a tarmac last summer. A similar incident ended in the deaths of seven puppies in 2010. The airline also was sued last summer over the death of a giant rabbit on a flight from London to Chicago.

In another public relations fiasco, United faced public backlash and congressional hearings last year for having a man dragged off a plane.