TAIPEI, Taiwan — Taiwan’s worst outbreak of the COVID-19 pandemic grew Thursday, with a worrisome 63 new cases not having a clear connection to existing cases.

The island raised its alert level this week, banning indoor gatherings of more than five people and outdoor gatherings of more than 10 people. Schools are shut for two weeks, and many people are working from home.

The majority of the cases in the latest outbreak have been discovered in the capital, Taipei, and neighboring New Taipei.

The island overall reported 286 new cases on Thursday that were transmitted domestically and more than 600,000 people are in quarantine because they were exposed to someone who was infected.

In the last week, the island has recorded more than 1,000 cases alone, accounting for more than a third of its pandemic total of 2,825.

Most cases last year were among travelers, and the island was hailed for its success in keeping out the virus, through robust public health measures like quarantines and contact tracing.