Hundreds of weather forecasters and other federal National Oceanic and Atmospheric Administration (NOAA) employees on probationary status were fired Thursday, lawmakers and weather experts said.

Cuts at NOAA appeared to be happening in two rounds, one of 500 and one of 800, said Craig McLean, a former NOAA chief scientist who said he got the information from someone with first-hand knowledge. That’s approximately 10% of NOAA’s workforce.