The fire alarm came at 2 a.m. Upon arrival, the house was already engulfed in flames, Norwegian media reported.
One resident of the house had already gotten out on his own.
"This is a very tragic event that affects us deeply. The police have initiated investigations, but it is too early to say what happened," said Morten Mørkved, operations manager for Levanger and Verdal police, in a press release, according to VG.
During the night, attempts were made to find the two firefighters, without success.
"This is something that should not happen, but it always involves a risk to be on the front line. It is deeply tragic," said the head of the operation, Thor Inge Oxholm Aas, to Norwegian TV2.
