Relatives of the Boston University junior from Salisbury who was critically injured in a New Zealand crash that killed three other students are agonizing as they await an update on her condition after she underwent brain surgery over the weekend, her grandmother said on Sunday.
‘‘Hellish,’’ said Annette Theriault, 74, of Beverly when asked to describe her family’s wait for news of Margaret Theriault, 21. ‘‘Hellish, that’s all. It’s not a very good Mother’s Day. ... You’ve just got to roll with the punches.’’
Meanwhile, a Boston University junior who witnessed the crash Sunday described a sight he said he will never forget.
“We saw people lying in the road and saw wounded people and just felt kind of helpless,” Evan White, who was riding in a second van carrying students, which was not involved in the crash, told the university website. “Our first impulse was to do whatever we could, but everyone had a sense of helplessness. I helped people away from the van. Others ran to a house to get help.”
Theriault, a retired nurse, said brain injuries are very unpredictable.
But, she said, ‘‘I’ve seen miracles and I’ve seen the worst of it. I’m just hoping a miracle happens.’’
A spokeswoman for Waikato Hospital in New Zealand would only say the student remained in critical condition there.
In a statement released by the hospital on Monday morning New Zealand time, Margaret’s parents, Todd and Deb Theriault, said their thoughts and prayers were with the families of the students killed in the crash.
They said they had arrived in New Zealand to be with their daughter, called Meg.
‘‘We’re here now and we’re supporting our daughter for as long as it takes,’’ they said in the statement. ‘‘She is a fit and stubborn young woman and we know she is getting the best care.’’
Annette Theriault said the entire family is grief-stricken.
‘‘Well, we’ve cried a lot,’’ she said. ‘‘And we’re waiting and waiting. That’s all we can do, and you pray.’’
Margaret Theriault’s aunt, Terri Killam, 52, of Danvers, was at the home of Annette, her mother, on Sunday, where family members were gathered anxiously awaiting news.
‘‘All we can do is ask you to pray for us,’’ Killam said. ‘‘That’s the only thing you can ask for.’’
Andrew Berkman, a BU undergraduate in the School of Management, where Theriault is enrolled, said in an e-mail that he studied with her in Sydney and also worked with her as a teaching assistant at the management school on the Boston campus.
‘‘She has a great sense of humor and she is strong willed,’’ Berkman wrote.
He said that strength could help her as she fights to recover from her injuries.
Kenneth W. Freeman, dean of the School of Management, said Theriault is a double major in accounting and finance as well as a dean’s host, a selective position in which she represents the school at various events.
‘‘She’s an exceptional, exceptional student,’’ Freeman said.
Theriault graduated from Newburyport High School in 2009 and was a member of the National Honor Society, principal Mike Parent said in a phone interview. He said classmates chose her to give a reflective speech at graduation, and that she was also known for her humor.
Theriault was one of eight BU students traveling in a rental van Saturday morning, New Zealand time, that was bound for Tongariro Crossing, the volcanic site used to portray Mount Doom in the ‘‘Lord of the Rings’’ movies.
Two other minivans were carrying additional students; the students in one stopped to help while those in the other went ahead, unaware of what had happened.
About 7:30 a.m. (3:30 p.m. Eastern Daylight Time on Friday) Stephen Houseman, a junior who was driving the van Theriault was traveling in, hit a patch of gravel and swerved too far right to correct his course, officials said.
He swerved left, then right again, trying to avoid an embankment. The van rolled.
Some of the students, probably not wearing seat belts, according to New Zealand police, were thrown out before the van came to rest wheels-up on the shoulder, debris scattered across the highway.
Three BU undergraduates — junior Austin Brashears, 21, of Huntington Beach, Calif.; Daniela Lekhno, 20, of Manalapan, N.J.; and sophomore Roch Jauberty, 21, of Paris, who grew up in California — were killed in the crash and five other students were injured, including Theriault.
Boston University junior Hope Thomason, a close friend of Lekhno’s, described her on Sunday as a wordsmith who also loved roses, green apples, and the singer John Mayer.
‘‘She was the most beautiful writer,’’ Thomason wrote in an e-mail.
‘‘Even just [her] text messages of advice should have been put in a novel. ... She had so much potential and so many gifts, this just isn’t how it was supposed to be.’’
Colin Riley, a BU spokesman, identified the other injured students as Houseman, the driver, of Massapequa, N.Y.; Alys McAlpine, 20, of Washington, D.C.; Emily Melton, 20, of Painesville, Ohio; and Kathryn Moldawer, 21, of Gainesville, Fla.
As of Sunday evening, McAlpine and Moldawer remained hospitalized, Riley said, and they could be released on Monday or Tuesday.
Kim Perks, a spokeswoman for New Zealand police, said the investigation into the cause of the accident will take some time.
Killam, Theriault’s aunt, said Sunday that the family remains hopeful for a positive outcome for her niece.
‘‘We’re waiting [for news] from halfway across the world,’’ Killam said.
‘‘At least we have hope. She’s still alive.’’Globe correspondent Matt Byrne contributed to this report. Travis Andersen can be reached at email@example.com. Follow him on Twitter @TAGlobe.