Emergency crews were called to the beach at, between Swansea and Cardiff on the Glamorgan coast, shortly before 5.30pm yesterday.
The death of a young woman who was hit on the head by rocks falling from a cliff was a "tragic accident," police said.
A spokesman for the Welsh Ambulance Service said: "We were called to an incident on a beach at Llantwit Major. It was a report involving a 24-year-old female where a rock had fallen on her head.
"Unfortunately she suffered fatal injuries from that."
A kitchen assistant at the Beach Cafe at Llantwit Major said a friend of the woman was treated for shock following the incident.
The cafe worker, called Nicola, said: "It was horrible. A lady was here with blood on her face. She was her friend. She was okay but she was in shock."
South Wales Police has appealed for anyone who was visiting the beach at the time to come forward.
Milford Haven Coastguard said it sent staff to assist police and ambulance crews, while the Wales Air Ambulance are also believed to have been called out.
In 2012, a young woman died after being buried by tonnes of rock following the collapse of a cliff on a beach in Dorset.
Charlotte Blackman, 22, from Derbyshire, was killed as horrified onlookers – including her father and boyfriend – tried to reach her before another huge section of cliff gave way.