The actor Carrie Fisher has reportedly suffered a heart attack on a flight to Los Angeles from London.

Her brother, Todd Fisher, said the 60-year-old Star Wars legend was receiving treatment in an intensive care unit of a Los Angeles hospital after suffering a medical emergency on the United Airlines flight from London on Friday.

Todd Fisher said his older sister was receiving excellent care, but he could not classify her condition.

He had earlier told reporters that she had been stabilized and was out of the emergency room.

But he later clarified his comments: “It’s not fair to say ‘stable’. I am not saying she is fine, or not fine,” he told Reuters by telephone. “She is in the ICU.”

There was no confirmation of the Star Wars actor’s condition from emergency services. Erik Scott, a spokesman for the Los Angeles fire department, told the Guardian: “At 12.11pm the Los Angeles fire department responded to LAX airport for a patient in cardiac arrest.

“Firefighters aggressively provided advanced medical life support and transported the patient to a local area hospital.”

It was reported by the LA Times that she was being treated at the UCLA medical Centre in Santa Monica.

A United Airlines statement said: “Medical personnel met United flight 935 from London to Los Angeles upon arrival today after the crew reported that a passenger was unresponsive.

“Our thoughts are with our customer at this time and any requests for additional information should be directed to local authorities.”

A number of unnamed sources spoke to news outlets. One who said they were not authorised to discuss the incident, told the Los Angeles Times Fisher was “in a lot of distress on the flight”.

People who said they had been onboard the plane detailed the incident on Twitter. One, the YouTube star Anna Akana, wrote: “She wasn’t breathing for 10 minutes or so. They were administering CPR up until we landed.

“So many thanks to the United flight crew who jumped into action, and the awesome doctor and nurse passengers who helped.”

Fisher, 60 and the daughter of the Hollywood couple Eddie Fisher and Debbie Reynolds, rose to stardom as Princess Leia in the original Star Wars trilogy. She recently published The Princess Diarist, her eighth book, about playing the role. She has also written for the Guardian.

She was returning to Los Angeles after being in the UK to film the third season of the British television comedy Catastrophe.