Tucson, Ariz. (AP) -- US Border Patrol officials are investigating an incident in which National Guard troops along the Arizona-Mexico border had to flee a group of armed people. The gunmen fled into Mexico.
The troops withdrew safely Wednesday night and no was injured.
Officials don't know who the gunmen were or why they approached the border post.
The area has been a busy one for marijuana seizures. Officials say agents have seized 124,000 pounds of marijuana there since October.
The Guard has been assisting the Border Patrol since mid-June, trying to make things more difficult for drug and human smugglers.
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