While San Mateo police have been slow to release information in the case of a family found dead inside a home on a quiet street Monday morning, some pieces are starting to come together via multiple sources.

The gruesome discovery of a man, a woman, and four-year-old twin boys all dead inside a home in San Mateo's Sugarloaf neighborhood was made by police Monday morning, during a welfare check. As KTVU now reports, that welfare check was called for by the grandmother of the two boys, who told police she couldn't reach the family and a new nanny had been unable to contact them as well.

A neighbor told KTVU that the grandmother had been the one to call 911 around 9 am Monday, requesting the welfare check.

San Mateo police confirmed Tuesday that the man and woman were both found deceased in a bathroom, both from gunshot wounds, and there was a 9mm pistol present. They have said that a cause of death for the two boys still has not been determined.

Police have been frustratingly cagey about the circumstances of the crime, but KTVU's sources confirm that it was a murder-suicide, and that the husband shot his wife before turning the gun on himself.

It sounds as though the murders may have occurred Sunday night, and the boys were reportedly found in a bedroom.

"Everyone is currently getting autopsies done, so we are waiting for that to determine a lot of things, like how many gunshot wounds," said San Mateo police spokesperson Officer Jerami Surratt, speaking to the San Mateo Daily Journal. "We can’t confirm 100% who was the suspect until we get that information back."

Surratt added, "There are speculations about [their relationship], but until we get the formal identification of everyone, we can’t confirm that this was a family or not until we get everyone identified."

No names have yet been released.

The murders occurred in a home on the 4100 block of Alameda de las Pulgas, and police almost immediately informed neighbors and the public that there was no threat to the public, that it was an isolated incident, and no suspect was being sought in the case.

The San Mateo Daily Journal notes that a similar murder-suicide involving a family with two kids, happened in the Shoreview neighborhood in 2005. In that case, 53-year-old Tony Richards killed his wife and two daughters before taking his own life, citing financial problems in a suicide note.

Previously: Husband, Wife, Four-Year-Old Twin Boys Found Dead In San Mateo Home

If you or someone you know may be struggling with suicidal thoughts, you can call or text "988" any time day or night to reach the Suicide and Crisis Lifeline, or chat online.