CIUDAD JUÁREZ, Mexico (AFP)— A Mexican immigration agent was killed on Monday in Juarez, on the US border, after asking a group of migrants to identify themselves, authorities said.

Three people have been detained over the killing, which occurred at 12:30 pm local time, the National Migration Institute (INM) said in a statement.

The agent was “assaulted by a group of foreigners when he asked them for their identification documents” at a checkpoint, the institute said.

The INM said that one of the suspects was a Colombian national while the other two were Venezuelan.

The border agent’s death comes less than a month before the inauguration of US President-elect Donald Trump, whose promised anti-immigration policies have raised uncertainty among thousands of foreigners arriving at the border.

Trump, who has likened border crossings to an “invasion” and used his campaign to amplify real and imagined instances of crime committed by immigrants, has pledged to carry out mass deportations once in office.