(NEWARK, N.J.) -- Two firefighters died and five others were injured while battling a blaze aboard a cargo ship docked in Newark, New Jersey, on Wednesday night, officials said.
While the cause of the fire is still under investigation, there is an indication the firefighters' equipment was incompatible with the European ship's fire suppression systems, sources close to the investigation told ABC News.
The New Jersey firefighters also weren't trained to handle fires that take place on cargo boats, a source said.
Newark Fire Chief Rufus Jackson confirmed the deaths during a press conference early Thursday, a few hours after it was announced that a search was underway for two firefighters at the scene.
City officials later identified the fallen firefighters as 45-year-old Augusta Acabou and 49-year-old Wayne Brooks.
"They went into the flames doing their jobs," Newark Public Safety Director Fritz Frage said during a press conference on Thursday morning.
Newark Mayor Ras Baraka described Acabou and Brooks as "two of our bravest."
"That image will forever be stamped in my mind for how dangerous this job is," Baraka told reporters about witnessing the two firefighters being carried off the ship. "Our hearts are broken."
Acabou served in the Newark Fire Division for 9 1/2 years and was assigned to Engine 16, Tour 1, according to city officials. Brooks was a veteran of the fire department for 16 1/2 years and was assigned to Ladder 4, Tour 1.
"So many broken hearts today-but none more broken than those belonging to the families of Augusto Acabou and Wayne Brooks, Jr., everyone who loved those two men, and their brothers and sisters in the fire department. Our hearts go out to all those who grieve their tremendous loss today," Baraka said in a statement.
The last time a Newark firefighter was killed on the job was in 2007.
Three other Newark firefighters were injured during the incident: Newark Fire Captain Dave Rogers, who suffered a burn to his foot; Newark Fire Captain Michael Spadavecchia, who suffered from heat exhaustion; and Newark Fire Captain Richard Cooper, who suffered respiratory distress and possible smoke inhalation.
Two firefighters from the Elizabeth Fire Department, W. White and J. Manes, suffered smoke inhalation, according to officials.
Firefighters were dispatched to the Port Newark–Elizabeth Marine Terminal at around 9:30 p.m. ET after receiving a report about multiple vehicles on fire aboard a ship named the Grande Costa D’Avorio. They managed to extinguish the main body of the blaze but the flames had extended to multiple levels of the vessel, according to Frage.
The United States Coast Guard also responded to the fire, describing the vessel in a Twitter post as a "roll on/roll off vehicle cargo ship."
At 10:25 p.m. ET the firefighters called a "Mayday" after two firefighters were trapped inside the ship followed by a second "Mayday" call 15 minutes later, city officials said.
Acabou was found by his cousin, who is also a firefighter, at 12:45 a.m. ET and transported to a hospital where he later died, according to officials. Brooks, Jr was found at 2:25 a.m. by a FDNY firefighter and also taken to the hospital where he died, according to officials.
As of 5:20 a.m. ET, the blaze was under control and firefighting operations were mostly completed, though crews were continuing to monitor the ship, the Newark Fire Department told ABC News.
The fire was contained in an area of the 11th and 12 floors of the vessel, which has a Halon fire suppression system.
The city's firefighters are trained to battle blazes on cruise ships and other vessels that contain living quarters but not ones that carry vehicles, according to Jackson.
"This was definitely a unique fire for us," the fire chief told reporters.
One of the issues encountered by firefighters was their two-and-a-half-inch fire hose lines weren't compatible with the European-made ship’s one-inch connections, according to the source.
The Newark firefighters were instead forced to use the fire hoses on the boat, which output less water and pressure than the firefighters were used to, according to the source.
Sailing under the Italian flag, the Grande Costa D’Avorio left the Port of Baltimore on Sunday and recently arrived in Newark. The ship was built in 2011 and is operated by the Grimaldi Group, a Naples-based company that describes itself as Italy’s largest ship-owning group.
ABC News' Victoria Arancio, Jessica Gorman and Josh Margolin contributed to this report.