WASHINGTON — The Baltimore fire department said on Thursday that they can’t determine the cause of the fire that killed six children in January.

“After months of an intensive comprehensive investigation, the cause of the fire is undetermined,” the Baltimore City Fire Department said in a statement.

The fire Jan. 12 in the three-story house at 4205 Springwood Ave. killed Bridgett Malone, 11; Amelia Malone, 10; 3-year-old twins Amanda and Zoe Malone; William Malone IV, 2; and 8-month-old Daniel Malone.

Katie Malone, the children’s mother, and three children escaped, though they were injured. Their father was at work.

Katie Malone is an assistant to U.S. Rep. Elijah Cummings, D-Maryland.

“Our heartfelt condolences continue to go out to the Malone family,” Baltimore Fire Chief Niles Ford said in the statement. “This was an overwhelming incident and a huge loss for the Malone family, the City of Baltimore and to the members of the Baltimore City Fire Department.”

“This unimaginable tragedy is shocking and heartbreaking to us all,” Cummings said in a statement no the day of the fire.