Two 'adventurous' sisters drowned after sneaking into a neighbor's swimming pool, police said. 

The unidentified girls, aged five and eight, were found unresponsive in the pool on Monday at a home on Gerhardt Drive in Pensacola, Florida. 

On Tuesday, police chief Eric Winstrom said that it was believed that the older sister climbed a fence into the property before letting her sister through a gate. 

He told a press conference: 'Not only do they have a privacy fence for the backyard, they have a fence for the pool specifically to keep young kids out.'

Winstrom said the neighbors were not at home at the time and that the yard was 'exactly what a safe backyard with a swimming pool would look like.'

The girls were given lifesaving measures after the authorities were called before being rushed to a hospital, both were pronounced dead.

Speculating on what happened in the pool he said: 'Is it possible that the younger one fell in and was struggling and the 8-year-old went in and tried to save her?"  

'If we were going through the possibilities, it's very possible the 8-year-old passed while trying to save her 5-year-old sister who was a less-proficient swimmer. I think that's a real possibility.'

They were spotted walking around the neighborhood an hour before they were found in the pool, Winstrom added. 

He continued: 'From a police investigation point of view, that's certainly helpful to know that there's no foul play, as far as no one was leading them to this pool, no one was trying to abduct them or anything.'

Winstrom said he does not expect criminal charges to be filed, adding: 'All the adults that are involved in this incident did the right thing and it still ended in tragedy.

'So I don't anticipate any criminal charges in this case. But this is preliminary.'

His department are continuing to investigate with autopsy results yet to be released to them. 

The local medical examiners office said their investigation was still pending when approached for comment by the Daily Mail.