Yes. If your business owns or leases vehicles, you're required in all states to carry liability coverage for damages your vehicles may cause to other people or their property.
What's the difference between liability, collision and comprehensive?
Liability covers damages your vehicles cause to other people or their property. Collision and comprehensive are options that cover damage to your vehicle by collision or anything else (hail, flood, even falling avocados.)
My employees drive their own cars on the job. Do I still need commercial auto?
Yes. Non-owned vehicle insurance protects your business if employees cause damages while driving their own cars. (Pro tip: you could be held liable even if your employees aren't strictly on a "work" errand.)