Four people were injured in an explosion thought to be caused by a gas leak in the Fair Park neighborhood of Dallas early Monday morning.
The explosion occurred at a duplex in the 3700 block of Spring Avenue shortly before 1 a.m., according to Jason Evans, a Dallas Fire-Rescue spokesman.
"Though the explosion is thought to be gas-related, its exact cause is currently undetermined," Evans said in a statement.
On Thursday, Evans released a new statement saying, "The source of the leak was determined to be an open valve in the living room. Despite this finding, the ignition source has not yet been determined; and as a result, the exact cause is still undetermined."
There were four people in the duplex at the time of the explosion, Evans said.
Two people were transported to Parkland Memorial Hospital, one of them with serious burns.
Two men are still in the hospital after a home explosion in south Dallas. An arson team with Dallas Fire Rescue has started the initial portion of the investigation @NBCDFW #Dallas #AtmosEnergy #HomeExplosion pic.twitter.com/sK3wcqPxe0— Courtney Gilmore (@CourtneyNBC5) April 2, 2018
The other two residents suffered minor injuries and went to the hospital on their own to get checked out.
“He just said he was just laying in bed, just went to bed and next thing you know it was just a huge boom,” said Dean Landrum, whose father suffered a shoulder injury.
"At first he thought that maybe somebody was shot somebody or something like that but then he realized the ceiling was caving in and falling in on him and the whole back off the house was gone,” said Landrum.
Atmos Energy crews responded to shut off the gas and investigate.
So far, Atmos says crews have not found any evidence of gas leaks outside the house, and arson investgiators from Dallas Fire Rescue continue to search for the cause.
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Surrounding homes haven't been evacuated at this time.
Last week, 25 homes and an apartment complex in northwest Dallas were evacuated after someone noticed a natural gas smell along Linda Drive.
Those evacuations were inside a large zone where Atmos crews replaced aging steel gas lines. A 12-year-old girl was killed in a house explosion reportedly caused by a gas leak.
In the two days leading up to Linda Rogers' death, Atmos discovered at least 28 leaks in the neighborhood, according to emails obtained by The Dallas Morning News.
Rogers' family has accused Atmos Energy of gross negligence in a lawsuit. An Atmos spokesperson said the company declines comment on pending litigation.