The representative of Pope Francis in the US led a cross-border Mass on Sunday in an effort to bring awareness to the plight of immigrants and refugees.

Archbishop Christophe Pierre, the Apostolic Nuncio to the United States, was the principal celebrant as the 3pm Mass got underway in both Nogales, Arizona and Nogales, Mexico.

At least 250 people showed up on the Arizona side, said Steff Koeneman, spokeswoman for the Diocese of Tucson.

It wasn't immediately clear how many came on the Mexico side. An altar was erected on both sides of the border.