United airlines is apologizing after a Houston family claims their dog died while in the cargo hold of one of their airplanes.

The plane was allegedly stuck on the tarmac at Bush Airport for two hours before taking off for San Francisco.

The family said in a Facebook post that there'd been trouble with the air conditioning in the cabin as they waited on a weather delay.

That post has since been deleted, but United Airlines did acknowledge the incident and released the following statement:

"We are so sorry to learn of Lulu's passing and have reached out to our customer to offer our condolences and assistance. We are deeply upset any time an animal suffers an injury while traveling with us and especially grieved in the rare instance that one passes away. We are conducting a thorough review of this incident."