Scattered gunfire and rock throwing erupted across the country Monday as thousands of independent truckers pulled their rigs off the highway to protest the Reagan administration's 5-cent gasoline tax. No serious injuries were reported. Nonstriking drivers organized convoys and ''SWAT teams'' to protect members.
Most branches of the Independent Truckers Association started their strike at midnight Sunday. Others, including the Ohio unit, were planning to go out at midnight Monday. Teamsters Union drivers vowed to keep working.