Washington (AFP) - A US Border Patrol boat came under heavy gunfire from the Mexican side of the Rio Grande early Friday, but no injuries were reported, the Customs and Border Protection agency said.
Agents saw four assailants with automatic weapons shoot more than 50 rounds at the marine unit as it patrolled the river demarcating the border near Fronton, Texas, a CBP statement said.
"The boat was hit several times but no one on board was injured," it went on.
There was no information on who fired on the vessel and the CBP did not say whether the US agents returned fire.
In a statement Mexico's foreign ministry said it regretted the "armed aggression" against the US agents and expressed relief that no one had been hurt.
Mexico's Security Secretariat and the foreign ministry were investigating alongside US officials, they said.
Such incidents have been rare along the heavily patrolled border, where drug and people smugglers from the Mexican side seek to avoid detection and border patrol officers avoid firing into Mexico.