A pro-Trump protester on Tuesday shredded a Mexican flag while others watched - some cheering, others trying to intervene to stop him - during the president's visit to the U.S.-Mexico border in California.

Trump supporters were gathered in Otay Mesa when a protester accidentally dropped a Mexican flag from a passing car, KTLA reported.

A man in a Trump hat and shirt reportedly said "F--- Mexico, this is America" as he shredded the Mexican flag with a pocket knife.

Crowds around him chanted "USA" while one man yelled, "They burn our flag in our country, burn theirs in ours," KTLA reported.

The move didn't sit well with other Trump supporters in the crowd, however, and at least two of them tried to intervene, according to the news outlet.

Two women, including one draped in a "Make America Great Again" flag, stopped the man from setting the flag on fire.

One of the women said she disagreed with what the man did and said it sent the wrong message, KTLA reported.

Protesters clashed with Trump supporters as the president made his inaugural visit to the country's most populous state and saw prototypes of the border wall.

Demonstrators were on each side of the border.