One person is believed to be trapped under rocks after a landslide at a beach.
Police, the fire service, ambulance service and the Coastguard were dealing with the incident near the Freshwater Beach Holiday Park at Burton Bradstock, near Bridport, Dorset.
The Maritime and Coastguard Agency said Portland Coastguard was told a person was trapped under the fallen rocks between Freshwater and Burton Bradstock in an emergency call received just before 12.30pm.
The incident comes two weeks after Somerset couple Rosemary Snell, 67, and Michael Rolfe, 72, were killed in a landslide at the Beaminster Tunnel just nine miles away.
In a joint statement Dorset Police and Dorset Fire and Rescue Service said: "At just after 12.30pm today Dorset Police were called to a report from the coastguard of a landslide by the Freshwater Beach Holiday Park.
"Officers, with assistance from the police helicopter, are currently working alongside Dorset Fire and Rescue Service and other agencies to search the area.
"The Urban Search and Rescue Team (USAR) from Devon and Somerset has also been deployed to this incident. This is a national resource."
The Maritime and Coastguard Agency said three Coastguard rescue teams and the Coastguard rescue helicopter based in Portland were at the scene in Lyme Bay.
A spokeswoman said: "Portland Coastguard received a report of a landslide between Freshwater and Burton Bradstock at just before 12.30pm.
"The landslide was reported to be 400 metres from Freshwater caravan park and the caller reported that a person was trapped under the fallen rocks.
"West Bay, Lyme and Wyke Coastguard Rescue Teams and their managers are currently on scene with the Coastguard rescue helicopter based in Portland. They are working with Dorset Police, Dorset Fire and Rescue Service, South Western Ambulance Service and the lifeboat from Lyme Regis to search for those who may be trapped and to keep the public away from the area surrounding the landslide."
A spokesman for the South West Ambulance Service NHS Foundation Trust said: "One person is reported as being trapped and the ambulance service is working in partnership with the other agencies on the scene to reach them as quickly as possible.
"We dispatched a number of vehicles to the Burton Bradstock area following a number of calls made to the service just after 12.30pm today, including the Dorset and Somerset Air Ambulance and the service's Hazardous Area Response Team, who are trained to deal with a whole manner of challenging scenes."
Witnesses said there had been one death at the site, which is known locally as Hive Beach.
A worker at the Hive Beach Cafe said: "We have heard from people working at the scene that there has been one fatality.
"There was significant rockfall.
"We are waiting to find out more information but it is terribly sad."
The landslide comes just over two weeks after severe flooding left much of the community under water.
Residents said that flood water surged to heights of about one metre at its worst, forcing home owners to flee and scattering vehicles through the village.
It is believed the folk singer and protester Billy Bragg still has a home in the area.
The beach forms part of the historic Jurassic Coast - from Swanage in Dorset to Exmouth in Devon - sections of which have been crumbling into the sea for years.
Last week, Dorset Council issued a warning to visitors and walkers of the risk of landslides, following the heavy deluge of rain.
The council said the western end of the Esplanade at West Bay, near Burton Bradstock, had been closed at the weekend "due to concerns about continuing land stability in the area following the exceptional wet weather".
The council, posting on its website on June 20, said it had found large overhanging rocks at the top of the cliff at the western end of West Bay Esplanade, which appeared "ready to fall".
The statement added: "Some of these have already broken free and are perched on other overhanging rocks.
"There is a large amount of fresh rock fall debris on the sloping section of the cliff. Some of this looks unstable.
"At the western end of the Esplanade, particularly when it is raining, inspections frequently find rocks up to 600mm long on the walkway."
A National Trust spokesman said: "Our thoughts are with all those involved in this tragic accident.
"Coastlines are dynamic and changing environments and it is impossible to predict when these kinds of events might occur.
"National Trust land at Burton Bradstock will remain closed whilst we assist the emergency services in whatever way we can."