A natural gas leak may have fueled an explosion that leveled a home in Manchester early Thursday, injuring a man and his three children who were getting ready for school.

Larry Adrian and his family escaped just after his house at 6 Hagers Mill Court, near Big Bend Road and Highway 141, erupted about 6:20 a.m.

The force sent debris into neighbors’ yards in all directions and triggered a fire that damaged houses on either side.

“The entire front yard was engulfed in flames,” said neighbor Craig Anderson. “The flames were leaping from the house at least twice the size of the house.”

Bloody footprints marked where the victims ran up the street to escape the flames.

Paramedics took the family to St. John’s Mercy Medical Center in Creve Coeur. Adrian and his daughter, Veronica, were treated for minor injuries and released. His son Bradley, 12, was in satisfactory condition, and son Ian, 14, in serious condition with burns to his body.

Firefighters evacuated about 25 homes nearby when crews detected natural gas in the sewers, officials said. Workers shut down utilities in the area for several hours.

Firefighters from at least a dozen departments responded. They put the flames under control then stood back so Laclede Gas workers could make the area safe.

West County Fire Protection District Chief Ken Baker said officials suspect that a spark ignited a slow natural gas leak.

“There are not a whole lot of other options that would cause that kind of an explosion,” Baker said.

Laclede Gas spokesman George Csolak said his company had not received any complaints of natural gas odor in the area. The company will investigate, he said. State utility regulators will look into it as well.

Residents returned to their homes Thursday afternoon. Laclede crews visited homes to assist homeowners in reigniting pilot lights on gas appliances.

An investigation of several similar explosions in west St. Louis County in 1999 resulted in an agreement between the Missouri Public Service Commission and Laclede Gas to replace 80,000 copper service lines. The line serving that house that blew up Thursday was plastic, officials said.