A house has collapsed following a suspected gas explosion, police have said.
A search for casualties is ongoing following the incident in Clayton-le-Woods, Chorley, on Friday afternoon, Lancashire Fire and Rescue Service said.
Lancashire Police said officers were called to Kirkby Avenue at about 1.30pm.
A fire service spokesman said seven fire engines are at the scene, along with the urban search and rescue team, search dogs, an aerial ladder platform and the air support unit.
People in nearby properties are advised to close windows and doors to avoid being affected by smoke.
A police spokesman said: “Our officers are at the scene, along with our colleagues from Lancashire Fire and Rescue Service and the ambulance service.
“A safety cordon has been put in place and nearby residents have been evacuated.”
Road closures are also in place and people are advised to avoid the area, police said.