United Airlines apologized Tuesday, following reports about a Colorado woman who said she was not allowed to leave a delayed flight by the airline after her infant son fell ill due to a rise in the cabin temperature. The alleged incident happened on Texas-bound plane from Denver International Airport on June 22.

The infant’s mother Emily France told the Denver Post on June 23 her baby had to be hospitalized due to overheating in the flight, which was delayed by half hour amid a heatwave in the city.

Read: Complaints Against Airlines Surge After United's Passenger-Dragging Incident In April

“There was just hot air coming from the vents,” France told the Post. “They were not equipped to handle it. … They couldn’t evacuate us. It was chaos. I really thought my son was going to die in my arms.”

“His whole body flashed red and his eyes rolled back in his head and he was screaming,” France reportedly said. “And then he went limp in my arms. It was the worst moment of my life.”

Four-month-old Owen was treated at a local hospital, where doctors said he did not have any medical condition but suffered from the heat, France told the newspaper.

On Tuesday United released a statement to NBC apologizing over the incident.

“This should never have happened,” the airline told the news outlet. “We are profoundly sorry to our customer and her child for the experience they endured. We are actively looking into what happened to prevent this from occurring again.”

However, United defended itself saying Owen was provided with medical care 16 minutes after the captain requested paramedics.

Prior to apologizing, United confirmed to the Post there was a medical emergency on the Texas-bound flight.

 “[A] child onboard flight 4644 at Denver International Airport experienced a medical issue while the aircraft was taxiing prior to takeoff. The pilot returned to the gate as our crew called for paramedics to meet the aircraft. Our thoughts are with the child and family, and we have been in contact to offer travel assistance,” the airline told the newspaper last week.

Read: United Airlines Crew Wrestled Violin From Passenger Aboard Flight

This is the latest in a series of incidents to mar United following a high-profile case, in which a passenger named David Dao was dragged from a flight by aviation police April 9. The violent dragging left Dao with a concussion and two broken teeth. A video of the incident went viral, following which United issued an apology.

Earlier this month, a violinist accused United security for wrestling her musical instrument away from her.

On June 13, United issued an apology after a video went viral showing a Houston-based employee of the airline pushing a 71-year-old passenger to the floor during an argument over a ticket. The argument happened about two years ago but was listed in a lawsuit filed in Harris County, Texas.