DENVER — The first gay couple granted a civil union in Colorado said their vows before hundreds of people early Wednesday morning at a the Wellington Webb Municipal Building downtown, where eager couples and members of the public filled the first-floor atrium lobby to celebrate the first legal unions.

The new law legalizing civil unions took effect at 12:01 a.m. Wednesday and both Denver and Boulder began issuing licenses immediately.

Fran and Anna Simon were among the first four couples to receive a civil union certificate and the first to say their vows a few minutes later in an official ceremony.

Wearing the white wedding dresses they wore at their commitment ceremony seven years ago and joined by their five-year-old son Jeremy, Fran and Anna fought back tears as their said their vows in a ceremony officiated by Denver Mayor Michael Hancock and surrounded by a flood of clicking cameras.

“Our commitment doesn’t change, but we will have a burden lifted off our shoulders,” Anna Simon said. “Loving and committed couples need legal protections.”

The statewide advocacy group One Colorado hosted the festivities, and the Denver clerk’s office remained open until 3 a.m. to issue civil union licenses to couples eager to take advantage of their rights under the new law.

More than 130 civil unions licenses were issued in Denver.

Couples were ushered into the clerk’s office in small groups, where they filled out paperwork and received their certificate, a moment that for many came with a quick kiss, a squeeze of hands or a few tears.

Signed certificates in hand, couples were then joined in official ceremonies performed before supporters and other couples in the atrium of the Wellington E. Webb Municipal Office Building.

U.S. Rep. Diana DeGette joined Hancock and local judges and magistrates in officiating civil union ceremonies.

Hancock said he was honored to be part of the landmark event.

“I’ve been a part of the effort to legalize civil unions in Colorado now for several years. I feel a tremendous amount of pride for the people of Denver to work with their legislators to finally pass this piece of legislation to allow people to love and live as they so choose,” he said.

The second ceremony Hancock officiated was for Courtney Law and Sonja Semion, both of whom volunteered for his 2011 campaign.

Both wearing white, the couple looked at each other through watery eyes, smiling through their vows before sealing their union with an emotional kiss.

“It was more overwhelming than I expected,” Law said. “The moment kind of hit me. To be here with hundreds of people cheering us on anonymously, to have the mayor officiating, it all was really incredible.”

Colorado is the eighth state to have civil unions or similar laws. Nine states and the District of Columbia allow gay marriage.

“This is very real,” Semion said. “We’ve been committed for years, but to have the actual law behind it, it’s just such a great privilege today.”

Gov. John Hickenlooper signed the bill in March, marking the culmination of a dramatic shift in Colorado, where in 1992 voters approved a ban on discrimination protection for gays and in 2006 made gay marriage illegal under the state constitution.

The legislation might have passed last year, were it not for House Republican leadership, which opted to shut down the House floor in order to avoid a final vote on civil unions, which had more than enough votes to pass.

One of the bill’s prime sponsors, House Speaker Mark Ferrandino, D-Denver, was on hand for the first ceremonies; he and his partner, Greg Wertsch, who is out of the country this week, plan to have their own ceremony on the House balcony later this month after the legislative session ends.

Colorado’s civil unions law allows unmarried couples, both gay and heterosexual, the ability to form civil unions and get rights similar to those of married couples. They include transferring property, making medical decisions, adopting children and qualifying for health insurance and survivor benefits.

But for many gay couples and gay rights advocates, the fight is not over.

Anna and Fran Simon, for example, who testified numerous times in favor of the civil union legislation, say they hope to get the chance to wear their wedding dresses one more time.

“Like most people growing up, you have a dream of falling in love and getting married, not getting a civil union,” Anna Simon said.

Courtney and Sonja, who now have a third anniversary to celebrate, agreed.

“We’re hoping one day soon to have a fourth anniversary,” Semion said.