By Jim Forsyth

SAN ANTONIO, Texas (Reuters) - A U.S. Customs and Border Protection helicopter was forced to make an emergency landing near the Mexican border after it was hit several times by gunfire, the FBI said on Saturday.

The helicopter was on an operational mission along the Rio Grande near Laredo, Texas, when shots from the ground struck it late Friday afternoon, Special Agent Michelle Lee said.

"The rounds penetrated and damaged the aircraft, forcing the pilot to make an emergency landing," Lee told Reuters. The pilot was not injured and no one on the ground was affected by the emergency landing, she said.

Lee said the FBI is investigating the incident, along with the Texas Rangers.

She declined to say what the helicopter's mission was at the time, and said all other aspects of the incident, including whether the gunfire came from the U.S. or Mexican side of the border, are part of the investigation.

The Texas National Guard was deployed to the border last fall in response to a spike last summer in refugees from Central America attempting to enter the United States illegally.

The Texas Legislature recently passed a bill that would replace the Guard with 250 Texas Department of Public Safety officers, as well as other assets.

(Editing By Frank McGurty and Digby Lidstone)