Lincolnshire police said they had not officially identified the bodies found Friday.
Preliminary reports indicate the victims are Elizabeth Edwards, 49, and her daughter Katie, 13, according to police.
The two teens have been arrested and are scheduled to appear at the Lincoln Magistrates Court on Monday.
A detective in charge of the investigation said authorities want to talk to anyone who may have seen activity at the home between Wednesday and Friday.
"Post mortem examinations will be carried out in due course but again I still need to speak to anyone with any information that might be relevant," Detective Chief Inspector Martin Holvey said.
The deaths sent shock waves through the small market town with a population of 29,000, Superintendent Paul Timmins said in a statement.
"The events that unfolded in Spalding yesterday have understandably generated a great deal of local concern and upset," he said.
"I would like to make clear that this type of crime is extremely rare and not something we often see. Indeed, we believe this is a completely isolated incident."
Police are conducting forensic investigations at the scene.