A California family is dead, authorities say, after parking at a CVS drug store parking lot in Garden Grove. The family, which included two young children, appeared to have been homeless, and the van they died in sat for “several days” before they were found.

From CBS Local, Los Angeles: A woman reported the van at about 8:30 p.m. after walking by and smelling a foul odor coming from it, Garden Grove police said. Responding officers saw the van, which had been backed into a space in the far corner of the lot, had its windows covered with blankets and a sunscreen before finding a man, a woman, a boy, and a girl dead inside, police Lt. Carl Whitney said.

 The victims did not appear to have any signs of trauma, Whitney said. Autopsies are pending and will determine the cause of death.

“It appears that the man backed into a parking stall, and they may have succumbed to either some carbon monoxide poisoning, because there’s no obvious signs of trauma,” Whitney told CBS2. “But based on what we’ve seen, it looks like it was a tragic accident at this point.”

The children were 2 years old and 8 months old.

The woman who made the report reported seeing the van “go in and out of the parking lot over the past month,” leading her to believe the family was homeless.