Jennifer Lopez and Marc Anthony, who have been married for four years and are the parents of twins, reportedly renewed their wedding vows in Las Vegas Sunday.

A representative for Caesars Palace told People magazine the singers reaffirmed their commitment to each other at the hotel's Forum Tower Penthouse at 3:15 a.m., following a night at Pure Nightclub.

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

Lopez gave birth to son Max and daughter Emme Feb. 22. Although the twins are the couple's first children together, Anthony has three other children from previous relationships.