Newark, N.J. — Two firefighters were killed and six others injured early Thursday battling a blaze on a cargo ship at Port Newark, authorities said.

The fire broke out around 9:30 p.m. Wednesday in multiple vehicles on the 10th floor of the Grande Costa D'Avorio, then spread to the two floors above, authorities said.

Officials confirmed that two firefighters, identified as Augusto Acabou, 45, and Wayne Brooks, Jr., 49, went missing but were eventually found and pronounced dead on the scene. 

"Unfortunately, we have a loss. This is a tragedy, something that I, as a chief, never wanted to express," Newark Fire Chief Rufus Jackson said.  

The Coast Guard confirmed Thursday night that at least six other firefighters were injured. Their conditions were not provided. 

As of Thursday evening, firefighters were still working to extinguish the blaze, the U.S. Coast Guard said, adding that the "upper decks" of the ship were believed to be the "primary source" of the fire. 

At the time of the fire, the ship was carrying an estimated 1,200 vehicles and 157 containers aboard that were slated to be exported, the Coast Guard said. There was not believed to be any electric vehicles or hazardous cargo aboard, the agency added. 

"This vessel was unique, because it's not like a residential ship or a yacht," Jackson said. "It was a vessel that held cars, vehicles, a large amount of vehicles."

CBS New York learned the Grande Costa D'Avorio traveled from Baltimore on a two-day journey. It can carry more than 47,000 tons. 

The ship was built in 2011 and sails under the flag of Italy because it's owned by one of the country's leading ship companies, a family-owned company called the Grimaldi Group. The company specializes in the maritime transport of vehicles and shipping containers. 

The port, officially called the Port Newark Container Terminal, is about 272 acres — the largest container port on the East Coast.

Local, state and federal agencies will work to determine the cause of the fire, the Coast Guard said.

New Jersey Gov. Phil Murphy ordered all U.S. and state flags to be flown at half-staff Friday in honor of the fallen firefighters. 

"Our prayers go out to them, to their families, to their brothers and sisters in the fire department who fought beside them tonight and probably many fires before this one," Newark Mayor Ras Baraka told reporters. "I saw acts of bravery and comradery today that are unparalleled. And it's very, very, very traumatic for all of us."  

In:
• New Jersey
• Fire
• Newark