Three people were found dead at a restaurant on Wednesday in Liulin county of Lyuliang, Shanxi province, according to the local publicity department, Xinhua News reported on Thursday.

Police received a call from a passerby at 5:15 am on Wednesday, saying three people had been found lying on the floor inside the restaurant, and that their condition was unclear.

Officers who arrived at the scene said they could smell gas and suspected the deaths may have been caused by gas poisoning. At 5:39 am, the emergency medical center confirmed that all three showed no signs of life.

An investigation is underway, and follow-up work is ongoing.