ROMA, Texas (AP) Border Patrol agents making a drug seizure near the border west of Roma have exchanged gunfire with smugglers in Mexico.

The Border Patrol said in a statement late Thursday that one day earlier agents were nearly run over by vehicles loaded with marijuana near the banks of the Rio Grande. Agents fired at the drivers and then gunmen across the river began shooting at them. The agents returned fire across the border. No agents were injured, but it was unknown whether anyone on the Mexican side was hit.

Agents found nearly 4,000 pounds of marijuana, but the drivers of the vehicles escaped.

Rosendo Hinojosa, chief patrol agent, said assaults on agents would not be tolerated and agents would continue to respond with appropriate force.