Flames raced through a home in this St. Louis suburb early Friday, killing a mother and her three children, authorities said.
Neighbors said they had to restrain the woman's boyfriend to keep him from running into the burning home to save them.
The woman, whose name was not immediately released, was 32 years old, Deputy St. Clair Coroner Curt Schildknecht said. He identified the children as a 9-year-old boy and two girls, ages 10 and 11.
Neighbors said the boyfriend told them he had left the house to run a brief errand and returned to find it ablaze shortly after midnight. Much of the home's roof was destroyed and the front awnings were melted.
The four bodies were found inside, firefighter Chris Burch said.
"There's nothing that guy could have done. We held him back, couldn't let him go. He would have been a victim, too," said neighbor Bill Moore, 57.
The woman worked as a nurse while raising the three children and attending school, said Tomicia Taylor, who said she was a family friend.