Nine people have been taken to hospital following a major gas explosion in Clacton.
Two people have been airlifted and are in a critical condition.
The blast is believed to have happened in Cloes Lane just after 8.30am today.
Two semi-detached houses are believed to have suffered major damage and a gas-fuelled fire is still burning at the scene.
An East of England Ambulance spokesman said: "Critical care has been given to two people following a house explosion in Clacton. They have been taken to Broomfield Hospital, and eight others have been taken to Colchester General Hospital (CGH) following the incident in Cloes Lane this morning.
A man, believed to be in his 70s, was airlifted to Broomfield Hospital in a life-threatening after being anaesthetised on scene by air ambulance paramedics. A woman, believed to be in her 50s, was taken to Broomfield with severe burns.
The other casualties were taken with serious and minor injuries to CGH. Injuries include burns, and trauma injuries such as broken legs.
Five ambulances, several ambulance incident officers, the hazardous area response team (HART) and two air ambulances attended the scene and treated casualties on scene before they were taken to hospital."
The Essex County Fire and Rescue service reported that search dogs are being used to search the rubble.
Other properties were damaged by flying debris.
Neighbours helped pull victims from the rubble.
Smoke is said to be billowing into the air from the site.
The fire service has reported multiple casualties and nearby residents are being evacuated from the scene.
One neighbour told the Gazette: "The house five doors from us just went bang.
"Our windows have been put through."
The witness was getting her children ready for school when the explosion happened.
Emergency services including paramedics, police and the fire brigade are at the scene.
Two air ambulances are on site, as well as National Grid technicians.
The area has been cordoned off while emergency services work at the site.
An Essex Police spokesman said: "Several houses have been damaged. There have been reports of casualties.
"The immediate area is currently being evacuated. People are advised to avoid the area while emergency services deal with the scene."
Essex County Fire and Rescue Service said a house at the centre of the blast was on fire, adding that there were multiple casualties.
The incident commander reported two semi-detached houses have been affected by the blast, causing a gas-fuelled fire, which is being allowed to burn under control.
A spokesman said: "Numerous other properties have been affected by flying debris and are being evacuated.
"Firefighters are searching the rubble and dealing with multiple casualties with various injuries. There are still people unaccounted for."
The fire service tweeted that two houses had been "flattened" and another badly damaged.
Some tweets coming in from Clacton:
My whole house just shook like an explosion gone off in Clacton or something! Anyone know anything??— Andrew Woodfield (@Ipswichwoody) February 5, 2014
Okay so that massive bang was a gas leak & a house blowing up? Pretty standard for a Clacton morning... 😂👌— J (@JasonnLeonardd) February 5, 2014
What was that loud bang followed by all the Fire engines and Police cars in Sunny Clacton-on-Sea? #sunnyclacton— Duncan Lawrence (@DuncanCars) February 5, 2014