Jennifer Lopez and Marc Anthony participants in the Nautica Malibu Tiathlon 2008, held at Malibu Beach. California, USA - 14.09.08

According to People.com, the couple held their new nuptials at Caesars Palace's Forum Tower Penthouse at 3:15 a.m. (GMT) Sunday (12Oct08), with two pals acting as witnesses.

A source tells the website: "It was totally a spur of the moment thing. They decided around 12:30 in the morning that they wanted to do it and started calling for ministers."

The couple welcomed their first children together, twins Max and Emme, in February (08).

Source: WENN