At least 37 people were injured in an explosion at a supermarket in Iran’s southern city of Shiraz on Saturday, the country’s state media reported. The head of the medical emergency center of Fars Province said that none of the injured people were in critical condition.

A gas leak is suspected to have caused the explosion. Mohammad Farokhzadeh, the head of the fire department in Shiraz, told a state television that a gas leak or an explosion of flammable items stored in the supermarket could have caused the explosion. An investigation was underway, he added.

The blast took place around 12.45 am (local time) in the city’s Hypermarket center. The explosion was heard in most of the neighborhoods of Shiraz and caused the supermarket walls to collapse. Videos shared on social media showed that the blaze had reached the second floor of the building, which was partly residential.