A Cardiff road was closed off and all the emergency services were on the scene after a medical incident at a house in the city.
The air ambulance landed nearby, but one patient was taken to the University Hospital of Wales in the city by road for further treatment.
Police, fire and ambulance crews were called to Kent Street, in the Grangetown area of the city on Monday morning.
The alarm was raised around 9.36am, and South Wales Fire and Rescue said they were called just before 10am after receiving reports of "concerns for a person’s welfare".
A Welsh Ambulance Service spokesperson said: “We were called to reports of a medical incident in the Grangetown area of Cardiff this morning, at approximately 9.36am.
"We sent one rapid response car, one emergency ambulance, our Emergency Medical Retrieval Team and the Wales Air Ambulance to the scene.
"One patient was taken by road to University Hospital of Wales, Cardiff for further treatment.”
Police said they had been called in to assist the ambulance service after a local resident had taken ill.
A spokeswoman for the fire service said that c rews from Cardiff Central and Malpas were sent.
A local resident said there are been a lot of "activity" in the street during the morning.
She said: "An air ambulance flew overhead and landed in The Marl. Kent Street was cordoned off and there were two more ambulances, two fire engines and a lot of police."
