**Update: Four children who died have been identified, click here to read that story.
Hartsville Fire Chief Jeff Burr says he will sit down with state police fire agents and go through evidence collected from the deadly house fire that claimed the lives of four children on Depot Street Wednesday afternoon.
We expect to have autopsy results Thursday for the children.
Burr says it could be some time before they determine a cause.
When firefighters arrived at the single-wide mobile home on Depot Street just before 2 p.m., it was already 75 percent involved.
When they got the fire out, they found the bodies of the children: one-year-old twin girls and their two and four-year-old brothers.
Relatives say the girls' bodies were found behind a dresser, and the bodies of the boys were found under a bed.
Firefighters were on the scene in four minutes and had the fire out within ten minutes, according to Hartsville spokesman Russell Cox.
Firefighters say they did all they could to save the children, but the flames were too intense.
"Anytime you have fatalities, it's hard for your first responders. When you have children involved, it's that much worse as it can get for first responders," said Darlington County Sheriff Wayne Byrd.
Neighbors tried to help as well.
"The whole trailer was engulfed in flames. Everybody was standing around. Rat, (a neighbor) he tried to get in, but he couldn't because of the flames," said neighbor Priscilla Isaac.
When firefighters arrived, the mother was in the front yard, according to Sheriff Byrd, but it's not clear if she was in the home when the fire started.
Family at the scene Wednesday were very emotional. One relative had to be carried away from the scene.
Depot Street was closed for seven and a half hours Wednesday afternoon as investigators worked at the scene.
Hartsville Police, the Darlington County Sheriff's Office and the State Law Enforcement Division are investigating the fire.
The American Red Cross is helping the family.