An explosion at a residential building injured seven people in the Pardisan neighbourhood of Qom city, Iran’s semi-official Fars news agency reported, going on to quote an unnamed source saying it was not the result of any Israeli attack.“Four residential units were damaged in the blast. Initial assessments show that the cause of the incident was a gas leak, and follow-ups are continuing in this regard,” the director of Qom’s fire department told Fars.The agency said the residents of the building were ordinary citizens.Iran’s regional arch-rival Israel has a record of assassinating Iranian nuclear scientists, whom it considers part of a programme that directly threatens Israel. Tehran maintains its nuclear programme is solely for peaceful purposes.Since the end of a 12-day air war last month between Iran and Israel, in which Israel and the United States attacked Iran’s nuclear facilities, several explosions have occurred in Iran, but authorities have not blamed Israel.“People should not worry about rumours (of Israeli attacks). If a hostile action occurs in the country, the news will immediately reach the people and alarm bells will simultaneously be activated in the Occupied Territories,” Fars quoted an unnamed Iranian source as saying following the blast in Qom.