Updated

The U.S. State Department has issued a new travel warning for Mexico that tightens restrictions on its employees in areas hit by drug gang violence.

The new rules include prohibiting U.S. personnel from traveling to certain towns and along some roads in the state of Jalisco, where drug gang battles have increased in recent months.

In addition, because of recent gang blockades, U.S. employees are allowed to travel between the Jalisco capital of Guadalajara and the city's airport only during daylight.

The warning released Friday includes similar warnings for seven other states, including San Luis Potosi, where gunmen killed a U.S. Immigration and Customs Enforcement agent and wounded another as they drove on a highway.