Some industries have since resumed operations but only around three in 10 small and medium-sized enterprises were back to work, industry ministry spokesman Tian Yulong said Monday.
On Friday, France's health ministry said three people who had recently travelled to China were confirmed to have contracted the virus -- the first cases in Europe.
The WHO said China faced a national emergency but stopped short of making a declaration that would have prompted greater global cooperation, including possible trade and travel restrictions.
The city government said it would call off events including temple fairs -- which have attracted massive crowds of tourists in past years -- urging citizens "to strengthen prevention and support".
Such accidents in fireworks factories are common, especially in the runup to the Lunar New Year, which this year falls on January 25.