Seeing the line stretching past Citibank and around the corner down Brattle Street, a group of hungry students burst into a sprint, eager to be among the first burrito enthusiasts to taste the offerings of the Square’s latest entrée into the world of fast-food Mexican: Chipotle.

Chipotle—the Denver-based burrito chain—is hosting its grand opening today. Yesterday, the restaurant handed out free burritos from 11 a.m. to 8 p.m., serving thousands of students, local residents and Chipotle devotees who made pilgrimages from around the area, despite the rain.

At times, the waiting time to get one of the hot, tin-foiled wrapped burritos topped 45 minutes.

Many of those waiting had never tasted Chipotle before, such as Michael D. Burks Jr. ’11.

“Boloco is like my number one spot right now,” he said.

But after waiting 15 minutes for a steak burrito, Burks was back in line—before even taking a bite—to wait again for a second.

Students came from Tufts and local high schools such as Cambridge Rindge and Latin. One teacher from Rindge and Latin brought her whole Spanish class to the restaurant and offered her students extra credit for doing a survey in Spanish about Chipotle, according to Andrea Catalano, the Chipotle employee overseeing the promotion.

A. Lowell Richardson, a freshman at the Berklee School of Music in Boston, was getting his money’s worth from free-burrito day, too. He had come over on the bus from Berklee and, after getting one burrito, got back in line for a second. He planned to wait to eat the second one, and left satisfied.

“The pain wouldn’t be worth the gain,” he said. “Boloco and Qdoba just don’t cut it.”

Some came prepared to wait. Erin R. Gilmour brought a copy of Jane Austen’s Sense and Sensibility with her. Charlotte Braun, standing next to Gilmour at the very end of the line, had brought the free magazine Stuff @ Night to keep her company.

Others could not be persuaded to wait in the long line. One man, who identified himself only as “Brian,” upon hearing that the wait for lunch would take up all of his lunch break, abandoned ship.

Many gave up when, around 12:30 p.m., the rain, which had dampened festivities all day, intensified.

“The rains came and that kind of killed a lot [of the promotion],” said James D. Burton, Chipotle’s manager. But he still had high hopes for the giveaway.

“I’m hoping to get the entirety of Harvard Square fed,” he said with a grin. “I want every other restaurant to shut down because they can’t handle it.”

To fight the rain, Chipotle staff handed out large Harvard umbrellas to many of the soaked burrito-waiters. Staff also brought around boxes of dozens of burritos and drinks periodically throughout the afternoon, to help shorten lines.

The event, which drew approximately 3,000 people, was publicized largely through a Facebook event Catalano created a few weeks ago, as he does for every Chipotle promotion in the area. Chipotle does not do much radio advertising and does no television advertising, meaning that it relies heavily on word of mouth, he said.

But not everyone found Chipotle up to snuff compared to the myriad of other Mexican food options in the Square. Brenda C. Maldonado ’10, a former Crimson news writer, said her burrito “was not delicious.”

And Ben, a student from the Belmont Hill School who asked that his last name not be used because he could get in trouble for skipping class, said after trying a Chipotle burrito, “Anna’s Taqueria is still the best.”

—Staff Writer Gabriel J. Daly can be reached at gdaly@fas.harvard.edu.