A mother, father and their two young children were found shot dead in an apparent murder-suicide, according to police in Texas. 

A baby-sitter called police Monday evening and requested a welfare check after not hearing from the family at their Houston home, and all four — including a 4-year-old and an 8-year-old — were found dead inside, according to the Houston Chronicle.

It was not immediately clear who was behind the killings, but police have said it appears to be a murder-suicide.

None of the victims has been identified as police continue to investigate what happened.

A neighbor said the family had not lived there long, but she had seen them out and about in the neighborhood.

“It’s very sad,” that neighbor told KHOU. “I just shake for the little kids and the family and we don’t know all the details. A lot of people know more, I’m sure, than we know, but it’s just a tragedy when anything like this happens.”

One neighbor told ABC 13 that the mother was pregnant, although police have not confirmed.