Iran issued its most dire warning yet Tuesday about the outbreak of the new coronavirus ravaging the country, suggesting “millions” could die in the Islamic Republic if the public keeps traveling and ignoring health guidance.

A state television journalist who also is a medical doctor gave the warning only hours after hard-line Shiite faithful the previous night pushed their way into the courtyards of two major shrines that had just been closed over fears of the virus. Meanwhile, Iran’s supreme leader issued a religious ruling prohibiting “unnecessary” travel in the country.

Roughly nine out of 10 of the over 18,000 cases of the new virus confirmed across the Middle East come from Iran, where authorities denied for days the risk the outbreak posed. Officials have now implemented new checks for people trying to leave major cities ahead of Nowruz, the Persian New Year, on Friday, but have hesitated to quarantine the areas.