A family from Texas says their 5-year-old dog died while it was in a cargo area of an airplane that was delayed on the hot tarmac for two hours, KTRK reported.

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The King Charles spaniel named Lulu died while the United flight was stuck at Houston's Bush International Airport on Sunday for two hours before leaving for San Francisco around 3 p.m., according to KHOU. The family also had another dog with animal cargo.

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The Washington Post reported that the Rasmussen  family wrote on Facebook about the incident saying there was a problem with air conditioning in the cabin that day. Wether or not the dogs were in the cargo hold during the entirety of the delay is not clear.

KHOU reported that the post, in which the family also said there was a weather delay, has since been removed.

The high temperature in Houston that day was 94 degrees. The family discovered that their dog had died when they arrived in San Francisco.

United said the following in a 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."