The Mercer County Coroner tells 21 News there is no indication of foul play in the deaths of two children and one adult who died in a house fire in Greenville during the pre-dawn hours on Friday.

Coroner John Libonati said the bodies of 35-year-old Diana Mayes-Britton, and her twin 11-year-old children Olivia and Jonathan Mayes were found in an upstairs bedroom, presumably trying to escape when their South Main Street home caught fire after 6 a.m. Friday.

An adult male was flown by medical helicopter to a Pittsburgh hospital for treatment.

The alarm came in at 6:13 a.m. when dispatchers were told that a two-story home on the 400 block of South Main Street was burning.

The first firefighter to arrive reported seeing heavy smoke, then that flames had spread through the house. Officials say the house is a "total loss" and that there wasn't a single room in the house that hasn't been touched by the fire.

Officials went on to say the damage appears to have originated internally in the rear portion of the home.

Authorities say it is the first time anyone has died in a fire in Greenville since 1996.

At around 6:30 a.m. a crew from the Jamestown Fire Department was called to assist along with a Rapid Intervention Team which is dispatched when firefighters are at extensive structure fires.

The State Fire Marshal is looking for the cause of the fire. 

The Greenville Area School District superintendent's office told 21 News that it has grief counselors at the elementary school for students today.

Stay connected with wfmj.com and 21 News for the latest on this developing story