Police are on the scene after a suspicious fire started at Arrans Solicitors on Waterhouse Street early this morning.
A police cordon was put in place outside the Crown Coffee House and Halifax YMCA shop, where open windows above Arrans Solicitors revealed blackened windows.
Trading at surrounding businesses continued soon afterwards.
A spokesperson for West Yorkshire Police said: "Officers remain at the scene and enquiries are ongoing. We are treating the incident as arson."
Earlier a spokesperson for West Yorkshire Fire Service said: "A crew responded to reports of smoke coming from a second floor window on Waterhouse Street at 4:20am this morning (Thursday).
"On arrival they found a fire at a commercial property and used two hose reels and four breathing apparatus."