Nebraska authorities have launched an investigation into a natural gas explosion that seriously injured two people, leveled a house and significantly damaged nearly 20 other homes in Lincoln.

Police are focusing on the home where authorities believe the explosion occurred Monday, the Lincoln Journal Star reported . Witnesses said the two homeowners were thrown from the house during the blast. Police said Thursday that both were hospitalized in medically induced comas.

Lincoln Police Chief Jeff Bliemeister said investigators have obtained a search warrant and are conducting interviews. Investigators also are evaluating financial and cellphone records, and sending evidence off for forensic testing, he said.

But the chief cautioned that the nature of the investigation isn't uncommon.

"(In) many, many of the investigations that we begin as criminal, we're looking to conclusively prove or disprove whether or not a crime was committed," Bliemeister said.

Tests have confirmed that the blast didn't start outside the home, because there were no issues with the house's delivery of natural gas.

Natural gas is an odorless gas and has an added chemical marker, which sometimes smells of rotten eggs, to help people detect leaks. Chief Fire Investigator Bill Moody said the severity of the blast suggests gas had been leaking for hours.

The blast scattered debris and caused damage to homes for several blocks. Police Capt. Mike Woolman expects one affected street to reopen by the weekend. Another closed street, being used as the staging area for authorities, should open by early next week.

"There's a lot of people with damaged homes in the surrounding area, and they're working with restoration companies and insurance companies to try to bring back some semblance of normalcy into their lives," Bliemeister said.


Information from: Lincoln Journal Star, http://www.journalstar.com