TUCSON, Ariz. – U.S. 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.

Mexican state governments study possibility of giving migrants GPS locators

MEXICO CITY -- Mexican officials are studying the possibility of giving global positioning systems to migrants thinking about crossing the border into the U.S.

Supporters of the idea say they could be used to help the Border Patrol agents locate migrants in trouble. Hundreds of Mexicans are killed each year trying to sneak illegally into the U.S. Some drown, while others die in the heat.

A Mexican university is developing the locators, which would be given to migrants for free. American officials haven't signed off on the plan.

Anti-immigration groups have criticized similar efforts to help migrants but Mexican officials deny it will encourage illegal migration.