A massive wave of job cuts got underway at US health agencies early Tuesday, with some employees receiving early morning emails that their jobs were eliminated and some unable to access the building when they arrived at work.

As they readied to leave work Monday, some workers at the Food and Drug Administration were told to pack their laptops and prepare for the possibility that they wouldn't be back.

The Trump administration on Tuesday began mass layoffs of 10,000 staff at US health agencies, with security personnel denying entry to some employees just hours after they received termination notices