Yale may be among the world’s top universities, but on Thursday, it was no match for a clumsy construction worker laboring near a key power line on Science Hill.

The University — and particularly its administrative offices — ground to a halt just before noon after a construction accident at Kroon Hall, the new home of the School of Forestry and Environmental Studies, knocked out power to much of central campus for much of the day and caused a chain reaction that later crippled the University’s phone system for several hours. No one was injured in the accident, officials said, but there was no shortage of inconvenience to go around.

As science labs plunged into darkness, the rest of Yale’s campus remained bright for at least an hour. Humanities students remained blissfully unaware of the misfortune that had befallen their science-loving peers. Still, whether sitting in seminars or dozing in lectures, they were only minutes away from the same fate.

The accident occurred at 11:45 a.m., when a piece of construction equipment operated by a subcontractor at the Kroon Hall work zone struck an underground high-voltage line, causing buildings on Science Hill to lose power immediately. The trouble cascaded across campus: At 12:43 p.m., power went out in William L. Harkness Hall. By 1 p.m., the outage had swept across most of Yale’s campus and the school’s telephone system went down, too.

Dining halls lost electricity during peak lunch hours, and most of central campus was affected.

“It’s one of these issues where it’s inconvenient, but it’s not catastrophic,” said John Bollier, the associate vice president for facilities operations. “It was just such that we had to go about the process of isolating [the problem], keeping it safe and getting the other buildings brought back online.”

Power and telephone service had been completely restored throughout the campus by about 4:30 p.m., officials said, and no additional interruptions in service were expected today.

But Thursday afternoon was much less pleasant. Facilities employees crisscrossed the campus in windowless vans, attempting to restore normalcy. The telephone system — which was back online shortly before 3 p.m. — was caused by the power outage, said Joseph Paolillo, senior director of infrastructure services for Yale’s Information Technology Services.

Power, meanwhile, took slightly longer to be restored in some parts of campus, posing particular problems in some laboratories on Science Hill, officials said.

“Primarily, in a situation like that, you want to proceed cautiously, and you want to make sure that safety is first and foremost,” said Louis Annino Jr., the director of facilities infrastructure. “Most of the facilities on the campus have redundant services to them. Carefully choreographing the steps to transfer the loads to alternates services — that’s what we did for the balance of the afternoon.”

William Cross, a Yale fire inspector, said the outages triggered fire alarms in most buildings, which officers spent the rest of the day deactivating.

“We have a printer that records if a fire alarm comes in, and it was spitting out a whole bunch,” he said.

While the outages posed no physical threats to students, one near exception drew almost a score of fire fighters and security personnel to Yale’s campus.

At 1 p.m., the wail of fire sirens engulfed Cross Campus, as five New Haven fire trucks and engines, an ambulance and two police cars converged in front of 451 College St.

Onlookers took photographs of the fire trucks while firefighters toting axes and oxygen tanks poured into the building.

Only a few minutes earlier, employees had phoned security to report an odor of electrical burning, New Haven Deputy Fire Chief William Ryan said.

University Secretary Linda Lorimer was also on the scene. She echoed Ryan’s comments, noting that employees had detected the odor in the building’s basement.

Mary Jane Stevens, a senior administrative assistant in the Comparative Literature Department who works in the building, said she and several other employees were having lunch in the basement at the time of the outage.

“The power went out, and we smelled smoke and heard crackling from a mechanical room,” she said.

Afterwards, Rose Carrion, another employee in the building, called security.

Officers determined there was no smoke, and by 1:15, all fire officials had left.

Students from all corners of Yale’s campus were frustrated by the outage, which interrupted lunches and classes alike.

Charlotte Clune ’11 was in WLH taking a midterm when the room suddenly went dark.

“I thought the teacher was trying to tell us that the exam time was over — it really threw me off,” she said.

On the other end of campus, Anna Moser ’11 was blocked from entering the Yale Center for British Art, which shut its doors to patrons during the outage. She noted that even non-Yale students were thwarted in their quest to learn.

“There was a group of small children, and they were supposed to go in and draw, but they couldn’t,” Moser said. “I felt bad that their artistic creativity was stifled by the lack of electricity.”