Jayme Closs: Hunting at the age of 13 after the murder of his parents

An increasingly desperate search is under way in the United States after the disappearance of a Wisconsin teenager and the murder of his parents.

The couple, aged 56 and 46, was found shot dead Monday in the family home around 1:00 local time (6:00 GMT).

Since the police search Jayme Closs, 13, who is "in danger".

They say that a 911 call and evidence of address suggest that she was in the house when the disruption took place.

On Tuesday, Barron County Sheriff, Chris Fitzgerald, said a dispatcher had received a call from a cell phone and heard a disturbance in the background, but no one had talked to them about directly.

But when the police arrived four minutes later, no guns or suspects were found on the scene and there was no trace of Jayme.

On Wednesday, the deaths of James and Denise Closs were officially declared homicide by a medical examiner.

At a press conference, police said they have received about 400 public information since the disappearance of the 13-year-old girl and that an Amber alert had been issued to her.

The alert indicated that she had been taken from her home early Monday morning to "strangers, probably with a gun".

Miami police said Tuesday that she "might have been seen" at a gas station Monday, 2,700 miles from her home.

But this request was later rejected by the Barron Sherriff County Office as "not credible".

"If it does not come from this podium, it's not credible information," said Sherriff Fitzgerald. "I can not stress this point."

The missing teenager has been described as about 1.5 meters tall and 45 kg (45 kg) with green eyes and blond hair pommed.

Local authorities said the investigators did not think she had run away and did not consider her a suspect.

"Our number one goal is to bring Jayme home, and no amount of information will be released unless we feel it's appropriate to help," Sherriff Fitzgerald said Tuesday.

Jayme and her mother attended a family birthday party together Sunday afternoon while James Closs was at work, Jayme's grandfather told The Associated Press.

Robert Naiberg said nothing seemed wrong at the meeting and that Jayme was "calm as always".