A black, female doctor says that a Delta Air Lines dal flight member wouldn’t believe she was a physician and prevented her from trying to treat a man who needed medical care during a flight, NBC reports.

Tamika Cross is an OB/GYN resident at Lyndon B. Johnson Hospital in Houston, Texas. During a flight, a passenger two rows in front of her cried out for help because her husband was unresponsive, Cross said in a Facebook post published over the weekend.

Cross stood up to help, but a flight attendant told passengers to “stay calm” because the incident was just a night terror. But soon afterwards, the same attendant was calling out to see if any doctors were on board who could help.

That’s when Cross says she was met with skepticism by the Delta crew member. “[O]h no sweetie put ur hand down, we are looking for actual physicians or nurses or some type of medical personnel, we don’t have time to talk to you,” Cross reported her as saying in her Facebook post.

When the crew pinged passengers once again to see whether a physician was on the flight, Cross was asked by the flight attendant to provide her “credentials” and explain exactly what type of doctor she was.

Cross was eventually asked to assist a white, male doctor who was also on board when the man continued to seem unresponsive. The man reportedly wound up being okay, and Cross says the flight attendant eventually apologized to her and offered her free miles (which she refused).

Delta said it was troubled by the allegations and is investigating the incident.

“We are troubled by any accusations of discrimination and take them very seriously,” said the company in a statement. “The experience Dr. Cross has described is not reflective of Delta’s culture or of the values our employees live out every day.”

Cross seems determined to follow up on the matter. “I don’t want SkyMiles in exchange for blatant discrimination,” she wrote. “Whether this was race, age, gender discrimination, it’s not right. She will not get away with this.”