Father, mother die in San Mateo murder-suicide, deaths of twin boys unclear: sources

San Mateo police found a father, mother and two 4-year-old twin boys dead inside a home, in what appears to be a murder suicide, two sources told KTVU.

The father fatally shot the mother in a bathtub and then turned the gun on himself, the sources said. Police confirmed they found a 9mm pistol and loaded magazine in the bathroom. A source told KTVU the weapon was legally purchased several months ago. 

Detectives have not officially revealed how the boys died, though a source said they were found in a bedroom and were not shot. 

In an unusual tragedy in this bedroom community, the family of four was found dead Monday inside a home on Alameda de las Pulgas around 9:13 a.m.

Police said a 9 a.m. 911 call spurred a welfare check at the location after someone reported they hadn't heard from the residents for some time.

Police arrived and checked the exits of the home and found no signs of forced entry.

Police would not say where that call came from. But a neighbor told KTVU a grandmother of the children asked for a welfare check because she could not reach the family, nor could a new nanny for the children.

Officers did tell the neighbors that this was an isolated incident and there was no threat to the public.

Neighbors were shaken up.

Matthew Sheldon and his daughter, Marianne, have both lived in San Mateo their entire lives and they say they've never seen anything like this. 

"There's hardly any deaths in this area ever," Matthew said. 

Other neighbors noted that San Mateo, despite how relatively safe and quiet, isn't immune to death or tragedy. 

"It seems like an isolated incident, but I’m really sorry things happened. It happens everywhere," said Thomas F. Lease.  "I’m not going to walk in fear now."

EDITOR'S NOTE: If you or a loved one is feeling distressed, call the National Suicide Prevention Lifeline. The crisis center provides free and confidential emotional support 24 hours a day, 7 days a week. Call the National Suicide Prevention Lifeline at 1-800-273-8255, or text 741-741.