Family of four deliberately gassed in a 'pre-planned' murder-suicide.

As the community mourns the tragic deaths of Maria Lutz, Fernando Manriques and their two young children, reports have emerged that the Sydney family may have been deliberately gassed.

Police discovered the four bodies, plus that of a dog, inside the family’s home in the northern Sydney suburb of Davidson yesterday morning.

There were reportedly no signs of violence, but according to The Daily Telegraph, a police source has indicated that numerous gas bottles were placed around the home.

Ms Lutz’s body was reportedly found alongside that of one of her children, while those of her husband and other child were discovered in separate rooms of the house.

“There was a lot of pre-planning that went into this,’’ the source said.

Police made the heartbreaking discovery after being alerted by staff at St Lucy’s Primary School that the children, Elisa, 11, and Martin, 10, hadn’t shown up for class, nor had Ms Lutz, 43, arrived for her shift in the school canteen.

“It’s extremely confronting,”  said Superintendent Darcy of Northern Beaches Local Area Command. “We consistently have these concern for welfare cases, and unfortunately in some cases this is what the police are confronted with.”

St Lucy’s principal, Warren Hopley, said the school has been left reeling by the tragedy.

“We’re absolutely devastated by the news. This is an exceptional family who have been at the school here for six years,” he told media outside the Wahroonga school.

“Mum was a very active member of the school. Almost the cornerstone of the school in many ways. She would always attend meetings, ran the tuckshop here. She was a very busy woman and (the children) had very high, complex needs.”

Elisa and Martin suffered from severe autism. Image: Facebook.

Elisa and Martin both suffered from severe autism, and reports have been circulating this morning that suggest Ms Lutz and Mr Manriques, 44, had been struggling to cope with the difficulties associated with their children's conditions.

Neighbour Sonja Perry told The Daily Telegraph that the couple, who moved to Australian from Colombia in 2005, had a lot on their shoulders.

“(She) used to tell me how hard it was on her and her husband,” Ms Perry revealed.

“She said it was a heavy thing on her heart and some days she found it impossible to cope. They were South American, such a lovely, friendly couple. I’m shocked to see police cars outside their house. They never caused anyone problems.”

Police have not publicly commented on a cause of death, nor indicated when the family is likely to have died.

A report is being prepared for the coroner.

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