A second incident of chlorine leak was reported at the Mumbai Port Trust (MbPT) warehouse on Thursday.
Eight people were hospitalised after the leak.
Officials said Thursday's gas leak was not as serious as the one reported the day earlier.
Seven of these are firemen, who were on duty when they inhaled the chlorine gas that escaped one of the cylinders.
"The firemen were complaining of breathlessness when they came in. But their condition is stable," said Dr Mukund Kelkar, chief medical officer, Mumbai Port Trust Hospital.
The eighth victim was admitted to the KEM Hospital.
"His condition is fine," said the hospital's dean, Dr Sanjay Oak.
Vinay Kajla, commandant of the Central Industrial Security Force (CISF), said the incident occurred at around 11 am, when five corroded chlorine cylinders were being neutralised. The chlorine in these cylinders was treated with caustic soda.
Officials said the wind acted as a catalyst and spread the chlorine fumes.
All the staff of the National Disaster Response Force (NDRF), MbPT, the CISF and the police left the spot for some time as a precautionary measure. Work on neutralising the gas in the cylinders had to be suspended for 45 minutes.
An eyewitness said the fumes were so dense that he could not see beyond eight feet.
Shahbuddin Ali Ahmed, assistant commandant of NDRF, however, said "Everything is under control. There was no major leak."
Of the 123 patients who had been admitted to various hospitals after Wednesday's leak, 97 were discharged on Thursday morning.
The J J Hospital, which had admitted 100 patients, discharged 85, while the Mumbai Port Trust Hospital discharged 12 of 23 patients.