The two employees — who remained unidentified Friday afternoon — were asked to shut off a gas valve after someone reported smelling gas, according to Los Angeles County Fire spokesman Al Yanagisawa.
The explosion, which was described as sudden flash fire, occurred in the pool area where scuba equipment is stored.
The employees suffered unspecified injuries, but a sheriff's department official said they were taken to Huntington Hospital in Pasadena to be treated for burns.
Yanagisawa said there was minimal damage to the building.
Sport Chalet released a statement hours after the explosion, calling it a “tragic event” that was being investigated by outside agencies.
“Our heartfelt thoughts and support are with our two employees who were hospitalized this morning following an explosion outside of our La Cañada Flintridge store,” the company said. “This is the first time in the company's 54-year history that such a tragic event has occurred.”
Company employees who emerged from the building later in the day declined to comment, saying they had been told not to speak to the media.
At an afternoon news conference, Sport Chalet Chief Executive Craig Levra, said the store could reopen as soon as Saturday.
Denise King, spokeswoman for Southern California Gas Co., said the utility tells customers to never attempt to control or repair a gas leak, or fix a damaged pipe or meter.
If customers smell gas or hear the hissing of a gas leak — or see a visual sign, such as dirt or water flying into the air — they should evacuate the area immediately, making sure to never light a match or use an electrical appliance, she added.
From a safe location, they should then call either the gas company at (800) 427-2200 or dial 911, King said.
-- Jason Wells, Mark Kellam and Tiffany Kelly