A maintenance worker suffered burns after an explosion in an apartment complex in Pomona Friday.

Police say when the man entered a room with a hot water heater there was an explosion. The fire inspector believes fumes from flammable cleaning materials the workers were using might have made their way inside the room with the hot water heater. The inspector says when a door of a concealed room is opened, it adds oxygen, which acts as a flashover and burns the fumes.

The man was taken by helicopter to Westchester Medical Center. Police say no one else was injured and there was no structural damage to the apartment.