INDIANAPOLIS — Splintered beams and boards on a piece of charred earth were all that remained Sunday where two Indianapolis homes were leveled in a blast that killed two people and rendered homes for blocks uninhabitable.

A backhoe raked through the rubble in the middle-class subdivision as clusters of firefighters and rescue workers weary from a long, chaotic day that began late the night before waited for their next assignment.

The two-story, brick-faced homes on either side of those demolished by the blast were ruins. One home’s roof was gone, a blackened husk left behind. On the other side of the gap, the side of a home was sheared off. Across the street, garage doors had buckled from the heat.

It wasn’t yet clear what caused the blast that shook the neighborhood at 11 p.m. Saturday. Residents described hearing a loud boom that blew out windows and collapsed ceilings. Some thought a plane had crashed or that it was an earthquake.

Alex Pflanzer, who was asleep when the nearby homes were leveled, said he heard his wife screaming and thought someone was breaking in his house. Grabbing his gun, he checked the house and saw the front door was standing open.

“I walked outside and all the houses were on fire,” he said.

Deputy Code Enforcement Director Adam Collins said as many as 31 homes were damaged so badly that they may have to be demolished.

The explosion damaged a total of 80 homes, he said. He estimated the damage at $3.6 million.

Officials did not identify the two people who were killed.

Deputy Fire Chief Kenny Bacon told reporters Sunday investigators haven’t eliminated any possible causes for the blast.