A man has suffered severe burns and others are feared to be trapped after a number of homes were damaged in a suspected gas explosion in Oldham.
Emergency services are at the scene of the "very serious" incident, which is believed to involve a number of terrace properties in the Shaw area.
A spokeswoman for the North West Ambulance Service said one patient had been taken by helicopter to Wythenshawe Hospital in Manchester with 80% burns.
"We are currently assessing the scene and working closely with other members of the emergency services, with our priority being to ensure people receive the medical help they need as quickly as possible," she said.
In a statement, Greater Manchester Fire and Rescue Service said: "One man has been rescued following a possible gas explosion in Shaw in Oldham.
"The control room has received numerous calls from members of the public and the initial information from the public is that it involves a number of terraced properties in Duchess Street with possibly people trapped."
Steve McGuirk, chief fire officer for Greater Manchester, said in a tweet: "Just had an update on the incident in Oldham - very serious, we have crews and search and rescue teams on scene working hard."
Superintendent Neil Evans of Greater Manchester Police said: "This is an ongoing search and rescue effort and we are offering our full support to the fire and other emergency services. Our main and immediate focus right now is to assist in ensuring those injured in the explosion get any medical assistance that they need.
"It is unclear how many people may have been caught up in this incident or what the cause is and as soon as we have any new information we will let people know. To speculate at this stage would not be helpful to those involved in the incident itself or the rescue effort."