A Lexington Avenue restaurant’s sprinkler system kept an early Wednesday morning fire in check until firefighters arrived and extinguished it, officials said. Firefighters found smoke coming from Ya Hala restaurant on Lexington Avenue upon arrival at 4:39 a.m., said Deputy Chief Frank Prezioso Firefighters investigated a hissing sound at first believing it to be a gas leak, Prezioso said. The hissing was coming from the sprinkler system, he said. Sprinklers limited the fire to the kitchen area, Prezioso said. The fire took a while to extinguish as it had worked its way above the drop ceiling, Prezioso said. The deputy chief also said fire crews searched the property for possible victims but found none. The fire was out by 6:30 a.m. Paterson and Passaic, assisted.