SUN VALLEY (CBSLA.com) —Los Angeles Fire Department crews Wednesday were responding to an apparent gas water heater explosion in the San Fernando Valley.

The incident took place around 11:15 a.m. at a yogurt shop that is under construction in the 8900 block of Glenoaks Boulevard, officials said.

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A gas company employee and two workers from the shop were installing a tank-less water heater when it exploded.

One of the injured men ran into a nail salon next door to ask them to call 911.

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“He had a lot of scarring. He lost hair. His whole face was on fire,” a woman from the salon said.

All three victims were transported to a local hospital with moderate burns to their face.

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Officials were investigating how the water heater exploded.