RIO DE JANEIRO, Brazil: A mob of 2,000 people burned tires, blocked roads and attacked federal agents who sought to crack down on illegal Amazon logging, but officials vowed Wednesday that riots would not halt law enforcement.

Brazil's Environmental Protection Agency abandoned efforts to audit logging companies and sawmills suspected of illegal logging on Tuesday after mobs surrounded its workers and tried to invade a sawmill in a "public revolt" in the Amazonian town of Tailandia, the agency said on its Web site.

Many of the rioters work in the area's saw mills, which could suffer as a result of the inspections. Sawmill owners provoked unrest by threatening to fire workers questioned by officials, the environmental agency said.

But the government pledged Wednesday to resume its so-called "Guardians of the Amazon" crackdown on the illegal logging in the world's biggest rain forest, said Flavio Montiel, director of the environmental agency.

The crackdown began last week, when 130 environmental workers began inspecting Tailandia's estimated 140 sawmills. Of 10 mills audited, five were fined for stocking lumber of unknown origin and for selling lumber without authorization, the environmental agency said.

It seized 13,000 cubic meters (17,003 cubic yards) of illegal lumber, including top Brazilian hardwoods — enough to fill 640 trucks, the agency said.

But inspectors were surprised Tuesday by "an enraged mob" that blocked roads and forced them to flee under the protection of 70 police officers. Gunfire broke out, but no injuries were reported, the agency said.

Protesters held signs proclaiming: "We are workers. We want to work."