PITTSBURGH (AP) — Authorities say a fire that severely damaged a Pittsburgh warehouse this week is considered suspicious. But it’s still not clear what caused the blaze in the Strip District, which was reported early Monday. Firefighters battled the blaze for nearly three hours before it was brought under control. Officials say that although the fire caused severe damage, it doesn’t appear as if it compromised the structure of the building, which was unoccupied and under construction. No injuries were reported.