About 100 buoys that the federal government planned to install as anti-immigration deterrents near Eagle Pass drifted into the Rio Grande, prompting officials to close two key bridges along the U.S.-Mexico border for about three hours, reopening them just after midnight Friday.

Eagle Pass shut down transit at the bridges while it worked to determine whether the buoys posed a threat, City Manager Homero Balderas said.

About 9,000 vehicles cross both bridges daily, transiting between Eagle Pass and Las Piedras.