NORTH HOLLYWOOD, LOS ANGELES (KABC) --Three people were injured following an explosion at a home that shook a North Hollywood neighborhood on Wednesday.
The blast occurred at around 8:30 a.m. at a residence in the 6700 block of N. Simpson Avenue.
A 24-year-old man was transported to an area hospital in critical condition. Two others, a 21-year-old man and a 55-year-old man, were treated and released at the scene.
The blast was so powerful that it blew a portion of the roof off at the back of the home, broke glass at at homes several doors down from the residence and knocked out power to some parts in the neighborhood.
"It was a huge, huge, massive explosion. You can feel the whole house moving back and forth maybe for two seconds," said Raymond Signor, a witness.
The cause of the explosion was under investigation.
"The brick wall that was standing between both properties and the neighboring property was knocked over by the force of the explosion. It was significant enough you can still smell the odor of chemical in the air," said David Ortiz with the Los Angeles Fire Department.
Authorities initially thought the explosion was related to drugs after discovering a marijuana growing operation at the home. However, officials later said they don't believe that was the origin of the explosion, describing the marijuana grow as very small in scale.
Investigators said they are now considering the possibility that the blast was sparked by a gas leak, adding that there was recent construction being done in or around the home.