A MOTHER, her three children and a friend escaped unharmed after a blaze ripped through their home while they slept.

Police believe the fire was started deliberately and say only a smoke alarm in the 32-year-old woman's three-storey flat in Whitchurch Way, Halton Lodge, saved them after an area just inside the front door was set alight.

"That they had a smoke alarm and it was working was really critical," said Det Sgt Adam Waller, investigating.

"Had they not been woken and raised the alarm the fire would have quickly taken hold."

The woman, her eight and 14-year-old daughters, her 11-year-old son and a 34-year-old female friend were all treated for smoke inhalation at Whiston Hospital and later discharged.

The flat suffered extensive smoke damage, particularly to the ground floor, but no other homes were affected.

Detectives probing the blaze, which was reported at 3.39am on Sunday, are treating it as 'suspicious' and are investigating the possibility that something was put through the letterbox.

Two local men, aged 21 and 19, had been arrested and subsequently released on bail in connection with the incident.

Anyone who saw anything suspicious either before or after the fire is asked to call Det Con Greg Thomas or Det Sgt Adam Waller at Runcorn specialist investigation unit on 01244-613 934 or Crimestoppers anonymously on 0800-555 111.