Firefighters got a call shortly before 3 a.m. about the fire at Brown’s Lobster Pound in Seabrook, New Hampshire. Francis Emond/Seabrook N.H. Fire Department via AP

A popular Seabrook, N.H. restaurant was seriously damaged in a fire early Sunday morning, authorities said.

The fire department was called to Brown’s Lobster Pound just before 3 a.m. for a heavy fire that had broken out in the kitchen and rear of the building, said Firefighter Jeremy Wright.

Approximately 12 fire trucks responded to the call, and due to the nature of the building and paper supplies stored inside, “it was a difficult fire to fight,” Wright said. “They were there working until the sun came up.”

Authorities do not know what caused the fire or the full extent of the damage. Wright said it included the entire kitchen and described it as a “compromised structure.” An investigation will begin on Monday, he said.

Bruce Brown II, the owner’s son, said these are peak months for the restaurant and it would remain closed for now.

“Thankfully nobody was hurt — that was the important thing,” he said.

The popular lobster joint, which employs about 40 people, has been running there since 1950 Brown said. The structure damaged in the fire was a later addition.

“We will rebuild,” he vowed.

Firefighters worked on a fire at Brown’s Lobster Pound. Francis Emond/Seabrook N.H. Fire Department via AP