Authorities in Minnesota said on Tuesday they have recovered “new evidence” in a fire that destroyed a historic synagogue a day earlier, The Associated Press reports.

Duluth Police Chief Mike Tusken did not specify what the evidence was, nor would he say if authorities thought foul play was involved in the fire at the Adas Israel Congregation in downtown Duluth.

Police are reviewing hundreds of hours of surveillance tape from nearby residences and businesses, and are trying to talk to witnesses, according to AP.

Also assisting are investigators from the US Bureau of Alcohol, Tobacco, Firearms and Explosives, which is standard when fires break out in places of worship.

The cause of Monday morning’s fire at the Adas Israel congregation, a Modern Orthodox/High Conservative synagogue, is unclear.

According to the St. Paul Jewish Federation, the synagogue has 75 members and daily prayer services.