A fire that claimed a Saskatoon house Tuesday night is being labeled as suspicious.

Fire crews responded just before 10 p.m. to the home in the 300 block of Avenue P South but the initial response was delayed after the trucks were blocked by a train crossing 20th Street and a second crew had to be dispatched, the Saskatoon Fire Department said in a news release.

The delay caused by the train meant the first fire engines did not arrive on scene until seven minutes after the call came in.

The house was engulfed in flames when firefighters arrived. Crews worked to prevent the fire from spreading to a neighbouring house before entering the home to attack the flames. The fire was extinguished just before midnight, but firefighters were back at the scene just before 7 a.m. Wednesday after a report of smoke coming from the structure.

A search of the house found no one inside at the time of the fire.

A damage estimate is not yet available.