U.S. officials in the southern state of Tennessee say they have arrested two men who had allegedly been plotting to kill African-Americans including Democratic presidential candidate Barack Obama.

The men were charged with possession of firearms, conspiracy to steal firearms, and threatening a presidential candidate.

Court records unsealed Monday say local officers arrested the two men last Wednesday. They say the suspects were already armed with a sawed-off shotgun, a rifle, and three pistols, and were planning to rob a gun store for more weapons.

Officials said the two suspects had plans to attack a predominantly African-American high school.

The records say the men talked of following up with a nationwide killing spree, culminating with the assassination of Barack Obama.

If elected November 4, Obama would become the nation's first African-American president.

In August, local and federal authorities in the city of Denver, Colorado, uncovered another possible plot against Obama. They arrested four people and seized a cache of weapons and illegal drugs.

Denver was the site of the Democratic National Convention that month.