Authorities say the fire broke out at 40 Boyd Street near Kennedy Boulevard just after noon.
The building is a 3-story wood structure and the fire quickly spread to four alarms and to two additional buildings.
A total of 50 firefighters suffered injuries. All suffered from heat exhaustion except for one who suffered an ankle injury.
"The fire originated in the basement and quickly climbed up to the attic," said Deputy Chief Charles Donahue.
Firefighter battled triple digit temperatures while fighting the blaze.
"Four alarm fire while it's (hot) outside, heat exhaustion and ankle injuries, thankfully no fatalities, but you just want to be out here supporting these guys," said Steve Fulop, Jersey City Mayor.
The cause of the fire is also not known at this time.
