MEXICO CITY, Mexico (AP) -- Mexican federal agents have arrested four Iraqis trying to sneak into the United States without proper documents, the government said Monday.

Wasim Francis Schamoun and Ivan Yalda, both 23, and Refon Chlil Oraha and Thaer Salem Yelda, both 27, were found on a bus in the northern city of Navajoa after police received an anonymous tip, the attorney general's office said in a statement.

The Iraqis were in Mexico illegally, the statement said.

Officials on Monday said they were investigating the background of the four and trying to determine how they got into Mexico...