The federal government should ban same-sex unions, said almost 1,000 Catholics, who gathered at a rally Saturday in support of marriage as the union of one man and one woman.

The day began with a morning mass, celebrated by Archbishop William J. Levada of San Franciso at Saints Peter and Paul Church. The crowd then took part in a march of several blocks. The participants walked in prayer, with rosaries and signs with pictures of the Virgin Mary and Jesus, reported the Associated Press.

Participants expressed their opposition to same-sex marriage. They criticized San Francisco Mayor Gavin Newsom and city officials, who illegally issued about 4,000 marriage licenses to same-sex couples between Feb. 12 and March 11. Rally participants called for a federal amendment to ban the unions, reported the AP.

The rally and march was organized by Your Catholic Voice, a nationwide organization with about 250,000 members.