One construction worker is dead and another is in serious condition following a roofing accident Wednesday morning at the Minnesota Vikings stadium site.

Mortenson Construction, the general contractor on the site, said that the two workers from North St. Paul-based Berwald Roofing Co. were injured at about 7:45 a.m. while working on the north side of the building.

All work on the project has been stopped.

"This is a very tragic day," Mortenson Senior Vice President John Wood told reporters late Wednesday morning.

Emergency responders gathered outside the stadium's construction site Wednesday morning. Tim Nelson | MPR News

Officials are still investigating what happened. But Wood said that the worker who died fell from the edge of the roof into what he described as a snow gutter below the main roof on the north side of the building.

Wood estimated the man fell about 50 feet but said that distance still needed to be verified.

Emergency responders reported the man was pronounced dead on arrival at the hospital, he added.

The other worker was injured while he was on the roof. Wood said he did not fall from the roof but "we don't know exactly what caused his injuries."

In the past five years, 16 compliance inspections at Mortenson work sites resulted in no citations or penalties, according to the Minnesota Occupational Safety and Health Administration.

Berwald Roofing was fined $2,100 in August last year for failing to provide safe measures on scaffolding.

Workers started streaming out of US Bank stadium shortly after 9 a.m. following a construction accident, August 26, 2015 Tim Nelson | MPR News

OSHA records say employees on scaffolding more than 10 feet above a lower level were not protected from falling through guardrails along all open sides or personal harnesses.

OSHA also fined Berwald for similar violations in 2013 and in 2012.

Wood said that he couldn't answer at this point whether the men involved in Wednesday's stadium accident were wearing safety harnesses.

Wood, along with the Vikings and the Minnesota Sports Facilities Authority, expressed condolences to the friends and families of the two men. About 1,200 people are working now on the stadium site, which is expected to open next year.

It's the second stadium construction death in Minnesota in two years. Another worker was killed in St. Paul building the new Saints stadium in Lowertown in September 2013.

The Vikings stadium has been under construction since December 2013 and is scheduled to be completed in July. These were the first significant injuries reported on the project.

Wood said work on the stadium may resume on Thursday but that the priority was to find out exactly what happened and ensure that it never happens again.

"A man lost his life on the project today," he added. "That simply shouldn't happen."

MPR News reporter Riham Feshir contributed to this report.