A University of California, Berkeley student is missing in Nice, France, following Thursday's terror attack that killed at least 84 people and injured scores of others, according to university officials.

Twenty-year-old Nicolas Leslie was among 85 Berkeley students attending a study abroad program nearby, officials said Friday. Three other Berkeley students in the group were injured in the attack, in which a gunman drove a truck through crowds leaving a Bastille Day fireworks celebration in the seaside tourist destination.

Friends tell NBC Bay Area that Leslie avoided being hit by the truck but was separated during the stampede and chaos that followed. They also say he was active on social media after the attack but has been silent since, which they describe as unusual. [[387002501, C]]

Leslie is a junior at Berkeley, majoring in the College of Natural Resources.

Berkeley spokesperson Robert Sanders said that staff with campus study abroad, risk services and student affairs offices were working with Leslie's family, students in France, the program director on the ground, local officials and U.S. consular officials to find him.

The Wall Street Journal reported that Leslie's uncle, Fabeo Bottini, has been going from hospital to hospital in Nice trying to get information about his missing nephew.

The Daily Beast reported that a friend of Leslie’s saw the 20-year old running through the streets of Old Nice. But Leslie's aunt, Bottini’s wife, said the student never returned to his student housing Thursday night.

Leslie's friend, Anoop Baliga, has been reaching out to Leslie via social media along with many others hoping to hear from him soon. Baliga says Leslie's last Snapchat story post was from a restaurant about 10 minutes away from the attack's location. He says there has been movement on his Facebook page, but he thinks it's because people are using his laptop to try and find him.

Chandrabh Akireddy, who knows Leslie from the Net Impact Berkeley Undergrad program at Berkeley, said a couple of his friends who were in the square with Leslie, who friends call Nick, checked in after the attack.

"Some people saw him escape ... One of the students said he ran off with Nick during the attack but they got separated," Akireddy said. "The guess seems to be that he is OK."

Akireddy's friends saw Leslie active on Facebook messenger after the attack.

"We're taking that as a good sign and hoping that his phone died or something, and that he's still hiding somewhere," he said. "He's a great guy, we're optimistic."

Akireddy said that Leslie spent his childhood between San Diego and Italy. He added he met Leslie after joining Net Impact last year.

Leslie's Facebook page shows that he studies at Berkeley, lives in Del Mar, California, and is from Milan, Italy. He attended Torrey Pines High School in San Diego.

Mustapha Khokhar, a friend of Leslie’s at Berkeley, said he received a Snapchat from Leslie at 1:20 p.m. PT Thursday, but that he hasn’t heard from him since. That radio silence is odd for someone who has been snapchatting — or “streaking,” as its often called — relentlessly over the course of his vacation.

“We had a 20+ day streak going,” Khokhar said. “He’s been essentially documenting his whole trip to me over snap. And that streak ended yesterday.”

Khokhar said it’s possible, but out of character, for Leslie to have accidently let his phone die.

“Nick isn’t the type to go AWOL and pass out with his phone dead,” he said. “The dude is attached to his phone … but I would hope that’s what happened.”

Khokhar, who has known Leslie for more than two years, described his friend as someone with a “heart of gold.”

“He’s one of the most genuine and sincere people I know,” he said. “If you need help with work he will be there. If you call him at 3 a.m. asking to be picked up ‘cause you’re drunk, he will be there.”

According to Sanders, two of the students — identified as Diane Huang, 20, and Daryus Medora, 21 — sustained broken legs and were receiving treatment at a hospital in Nice.

A third, 23-year-old Vladyslav Kostiuk, suffered a broken foot.

Kostiuk posted a photo of his injury on his Facebook page, with the caption: "I would say only one thing: I was lucky, I'm alive, unlike other people that were walking with me. Just got out from a surgery. Picture: in a casino where I was taken first."

Paige Basconcillo, a Berkeley student from Bakersfield, California, who is also in the Study Abroad group, has been tweeting about Leslie as well, asking people in Côte d'Azur (the French Riviera) to search for him.

All of the students in the study abroad program were attending a 15-day program on Entrepreneurship and Innovation in Europe, part of the international European Innovation Academy, which was suspended to observe the three days of national mourning in France.

The program will go on through its planned end date of July 24, university officials said, but the campus has offered to bring home any students who wish to leave. So far, three students have opted to return home to the U.S.

UC Berkeley officials said in a statement late Friday that a representative of the study abroad program is heading to Nice to support the students, who experienced Thursday's horror.

UC Berkeley student Nick Leslie is missing following the Nice attack in France. His friend, Anoop Baliga, has been reaching out to Leslie via social media along with many others hoping to hear from him soon.

University Vice Provost Cathy Koshland and Dean of Students Joseph Defraine Greenwell joined the Bay Area community to express sympathy to to all the students, families and the French community who have been affected by this “tragic event” and “senseless violence.”

A message posted by Berkeley student Abhinav Kukreja on Facebook talks about Leslie missing since Thursday's attack.

"We know he successfully avoided colliding with the truck, but we lost him during the stampede and chaos that follow. Please share this so Nick an get back to his friends and family," Kukreja wrote.

Recent terrorist attacks have impacted other Berkeley students. Berkeley sophomore, Tarishi Jain, was among 20 hostages killed by Islamist militants in Dhaka, Bangladesh on July 1.

Gillian Edavane and Ryann Vargas contributed to this report.