A gas explosion in a sports complex in Iran's capital, Tehran, has killed three workers, Iranian state television reported.
It said the the blast occurred after heating gas leaked during repair work in a boiler room late on August 7.
Iran has an aging infrastructure, which it has struggled to maintain in working order through years of Western sanctions. Safety measures are also poorly enforced in Iran.
In July, five people were killed by a leakage of toxic gas and fire in two separate incidents in Tehran.