Two Newark firefighters have died battling a blaze on a massive cargo ship carrying vehicles in the port of Newark, New Jersey, officials said.

"Members made an attempt to extinguish the fire but got pushed back by the intense heat. Two firefighters were lost while conducting this action of backing out of the structure," Newark Fire Chief Rufus Jackson said, according to WABC.

The firefighters responded to a call around 9:25 p.m. Wednesday of multiple vehicles on fire on a roll-on/roll-off cargo ship named the Grande Costa D'Avorio, the US Coast Guard said in a statement.

"Multiple vehicles reported to have caught fire, all crew accounted for," the statement said. The military branch said the fire had been knocked down but a search was underway for two firefighters.

Incidents in which multiple firefighters die are relatively rare. In 2022, there were six incidents with multiple fatalities, including the deaths of three firefighters in Baltimore in January 2022 when a blazing building partially collapsed.

New Jersey Gov. Phil Murphy issued a statement grieving the deaths.

"Our hearts are heavy today as we mourn the loss of two Newark firefighters, who made the ultimate sacrifice in the line of duty. Tammy and I extend our deepest condolences to their families and loved ones, and we pray that those injured have a full and speedy recovery," he said. "This tragedy is a painful reminder of the dangers our firefighters face and their remarkable courage."

Newark Mayor Ras Baraka said his thoughts and prayers go out to the families of the firefighters.

"I saw acts of bravery and camaraderie today that are unparalleled. And it's very, very, very traumatic for all of us," Baraka said, according to WCBS.

A spokesperson with The Port Authority of New York and New Jersey told CNN in a phone call that it responded to the scene of the fire Wednesday around 9:38 p.m. ET along with other local mutual aid partners.

CNN has reached out to the Newark Department of Public Safety for more information.