Arizona Governor Janet Napolitano has released details on the January 3 encounter between National Guard troops and an armed force from Mexico:

According to the statements, the armed group [of eight people] wore bulletproof vests and carried automatic weapons as they approached an entrance-identification site manned by the four National Guardsmen.

As they approached, the armed men "split into two groups to surround the site," said the statement from the National Guard government liaison.

Then, as the Guardsmen were putting their gear into the vehicle to leave, one of the armed men approached to within 40 feet, the National Guard report said.

The report goes on to say: "Both groups kept their weapons 'ready low' and never pointed them at each other. No shots were fired."

The account has been confirmed by the Border Patrol and the NG, and they point out that the Guardsmen were armed (but don't say whether they had bullets). They left the area and called in the BP, who tracked the group as they returned to Mexico.